diff --git a/ui-ngx/src/app/modules/home/components/device/device-credentials-lwm2m-server.component.html b/ui-ngx/src/app/modules/home/components/device/device-credentials-lwm2m-server.component.html
index a40ce4cb69..429a13ddb2 100644
--- a/ui-ngx/src/app/modules/home/components/device/device-credentials-lwm2m-server.component.html
+++ b/ui-ngx/src/app/modules/home/components/device/device-credentials-lwm2m-server.component.html
@@ -28,27 +28,18 @@
     <mat-form-field class="mat-block">
       <mat-label>{{ 'device.lwm2m-security-config.client-publicKey-or-id' | translate }}</mat-label>
       <textarea matInput
-                #clientPublicKeyOrId
-                [maxlength]="lenMaxClientPublicKeyOrId"
                 cdkTextareaAutosize
                 cdkAutosizeMinRows="1"
                 cols="1"
                 formControlName="clientPublicKeyOrId"
                 required>
       </textarea>
-      <mat-hint align="end">{{clientPublicKeyOrId.value?.length || 0}}/{{lenMaxClientPublicKeyOrId}}</mat-hint>
       <mat-error *ngIf="serverFormGroup.get('clientPublicKeyOrId').hasError('required')">
         {{ 'device.lwm2m-security-config.client-publicKey-or-id-required' | translate }}
       </mat-error>
       <mat-error *ngIf="serverFormGroup.get('clientPublicKeyOrId').hasError('pattern')">
         {{ 'device.lwm2m-security-config.client-publicKey-or-id-pattern' | translate }}
       </mat-error>
-      <mat-error *ngIf="(serverFormGroup.get('clientPublicKeyOrId').hasError('maxlength') ||
-            serverFormGroup.get('clientPublicKeyOrId').hasError('minlength'))">
-        {{ 'device.lwm2m-security-config.client-publicKey-or-id-length' | translate: {
-          count: lenMaxClientPublicKeyOrId
-        } }}
-      </mat-error>
     </mat-form-field>
     <mat-form-field class="mat-block">
       <mat-label>{{ 'device.lwm2m-security-config.client-secret-key' | translate }}</mat-label>
@@ -61,17 +52,18 @@
                 formControlName="clientSecretKey"
                 required>
       </textarea>
-      <mat-hint align="end">{{clientSecretKey.value?.length || 0}}/{{lengthClientSecretKey}}</mat-hint>
+      <mat-hint [fxShow]="serverFormGroup.get('securityMode').value === securityConfigLwM2MType.PSK" align="end">
+        {{clientSecretKey.value?.length || 0}}/{{lengthClientSecretKey}}
+      </mat-hint>
       <mat-error *ngIf="serverFormGroup.get('clientSecretKey').hasError('required')">
         {{ 'device.lwm2m-security-config.client-secret-key-required' | translate }}
       </mat-error>
       <mat-error *ngIf="serverFormGroup.get('clientSecretKey').hasError('pattern')">
         {{ 'device.lwm2m-security-config.client-secret-key-pattern' | translate }}
       </mat-error>
-      <mat-error *ngIf="(serverFormGroup.get('clientSecretKey').hasError('maxlength') ||
-            serverFormGroup.get('clientSecretKey').hasError('minlength'))">
+      <mat-error *ngIf="serverFormGroup.get('clientSecretKey').hasError('length')">
         {{ 'device.lwm2m-security-config.client-secret-key-length' | translate: {
-          count: lengthClientSecretKey
+          count: allowLengthKey.join(', ')
         } }}
       </mat-error>
     </mat-form-field>
diff --git a/ui-ngx/src/app/modules/home/components/device/device-credentials-lwm2m-server.component.ts b/ui-ngx/src/app/modules/home/components/device/device-credentials-lwm2m-server.component.ts
index 267650eef7..7c6ad485f3 100644
--- a/ui-ngx/src/app/modules/home/components/device/device-credentials-lwm2m-server.component.ts
+++ b/ui-ngx/src/app/modules/home/components/device/device-credentials-lwm2m-server.component.ts
@@ -16,6 +16,7 @@
 
 import { Component, forwardRef, OnDestroy } from '@angular/core';
 import {
+  AbstractControl,
   ControlValueAccessor,
   FormBuilder,
   FormGroup,
@@ -29,8 +30,6 @@ import {
   KEY_REGEXP_HEX_DEC,
   LEN_MAX_PRIVATE_KEY,
   LEN_MAX_PSK,
-  LEN_MAX_PUBLIC_KEY_RPK,
-  LEN_MAX_PUBLIC_KEY_X509,
   Lwm2mSecurityType,
   Lwm2mSecurityTypeTranslationMap,
   ServerSecurityConfig
@@ -62,9 +61,8 @@ export class DeviceCredentialsLwm2mServerComponent implements OnDestroy, Control
   securityConfigLwM2MType = Lwm2mSecurityType;
   securityConfigLwM2MTypes = Object.values(Lwm2mSecurityType);
   lwm2mSecurityTypeTranslationMap = Lwm2mSecurityTypeTranslationMap;
-  lenMinClientPublicKeyOrId = 0;
-  lenMaxClientPublicKeyOrId = LEN_MAX_PUBLIC_KEY_RPK;
   lengthClientSecretKey = LEN_MAX_PRIVATE_KEY;
+  allowLengthKey = [32, 64, LEN_MAX_PSK];
 
   private destroy$ = new Subject();
   private propagateChange = (v: any) => {};
@@ -134,21 +132,15 @@ export class DeviceCredentialsLwm2mServerComponent implements OnDestroy, Control
         this.serverFormGroup.get('clientSecretKey').disable();
         break;
       case Lwm2mSecurityType.PSK:
-        this.lenMinClientPublicKeyOrId = 0;
-        this.lenMaxClientPublicKeyOrId = LEN_MAX_PUBLIC_KEY_RPK;
         this.lengthClientSecretKey = LEN_MAX_PSK;
         this.setValidatorsSecurity(securityMode);
         break;
       case Lwm2mSecurityType.RPK:
-        this.lenMinClientPublicKeyOrId = LEN_MAX_PUBLIC_KEY_RPK;
-        this.lenMaxClientPublicKeyOrId = LEN_MAX_PUBLIC_KEY_RPK;
-        this.lengthClientSecretKey = LEN_MAX_PRIVATE_KEY;
+        this.lengthClientSecretKey = null;
         this.setValidatorsSecurity(securityMode);
         break;
       case Lwm2mSecurityType.X509:
-        this.lenMinClientPublicKeyOrId = 0;
-        this.lenMaxClientPublicKeyOrId = LEN_MAX_PUBLIC_KEY_X509;
-        this.lengthClientSecretKey = LEN_MAX_PRIVATE_KEY;
+        this.lengthClientSecretKey = null;
         this.setValidatorsSecurity(securityMode);
         break;
     }
@@ -157,25 +149,28 @@ export class DeviceCredentialsLwm2mServerComponent implements OnDestroy, Control
   }
 
   private setValidatorsSecurity = (securityMode: Lwm2mSecurityType): void => {
+    const clientSecretKeyValidators = [Validators.required, Validators.pattern(KEY_REGEXP_HEX_DEC)];
+    const clientPublicKeyOrIdValidators = [Validators.required];
     if (securityMode === Lwm2mSecurityType.PSK) {
-      this.serverFormGroup.get('clientPublicKeyOrId').setValidators([Validators.required]);
+      clientSecretKeyValidators.push(this.maxLength(this.allowLengthKey));
     } else {
-      this.serverFormGroup.get('clientPublicKeyOrId').setValidators([
-        Validators.required,
-        Validators.pattern(KEY_REGEXP_HEX_DEC),
-        Validators.minLength(this.lenMinClientPublicKeyOrId),
-        Validators.maxLength(this.lenMaxClientPublicKeyOrId)
-      ]);
+      clientPublicKeyOrIdValidators.push(Validators.pattern(KEY_REGEXP_HEX_DEC));
     }
 
-    this.serverFormGroup.get('clientSecretKey').setValidators([
-      Validators.required,
-      Validators.pattern(KEY_REGEXP_HEX_DEC),
-      Validators.minLength(this.lengthClientSecretKey),
-      Validators.maxLength(this.lengthClientSecretKey)
-    ]);
+    this.serverFormGroup.get('clientPublicKeyOrId').setValidators(clientPublicKeyOrIdValidators);
+    this.serverFormGroup.get('clientSecretKey').setValidators(clientSecretKeyValidators);
 
     this.serverFormGroup.get('clientPublicKeyOrId').enable({emitEvent: false});
     this.serverFormGroup.get('clientSecretKey').enable();
   }
+
+  private maxLength(keyLengths: number[]) {
+    return (control: AbstractControl): ValidationErrors | null => {
+      const value = control.value;
+      if (keyLengths.some(len => value.length === len)) {
+        return null;
+      }
+      return {length: true};
+    };
+  }
 }
diff --git a/ui-ngx/src/app/modules/home/components/device/device-credentials-lwm2m.component.html b/ui-ngx/src/app/modules/home/components/device/device-credentials-lwm2m.component.html
index 9bc5c799ac..b588f1af72 100644
--- a/ui-ngx/src/app/modules/home/components/device/device-credentials-lwm2m.component.html
+++ b/ui-ngx/src/app/modules/home/components/device/device-credentials-lwm2m.component.html
@@ -53,7 +53,8 @@
                   formControlName="key"
                   required>
         </textarea>
-        <mat-hint align="end">{{key.value?.length || 0}}/{{lenMaxKeyClient}}</mat-hint>
+        <mat-hint *ngIf="lwm2mConfigFormGroup.get('client.securityConfigClientMode').value === securityConfigLwM2MType.PSK"
+                  align="end">{{key.value?.length || 0}}/{{lenMaxKeyClient}}</mat-hint>
         <mat-error *ngIf="lwm2mConfigFormGroup.get('client.key').hasError('required')">
           {{ 'device.lwm2m-security-config.client-key-required' | translate }}
         </mat-error>
diff --git a/ui-ngx/src/app/modules/home/components/device/device-credentials-lwm2m.component.ts b/ui-ngx/src/app/modules/home/components/device/device-credentials-lwm2m.component.ts
index 99123a5db3..ff5fba9bdd 100644
--- a/ui-ngx/src/app/modules/home/components/device/device-credentials-lwm2m.component.ts
+++ b/ui-ngx/src/app/modules/home/components/device/device-credentials-lwm2m.component.ts
@@ -31,7 +31,6 @@ import {
   getDefaultServerSecurityConfig,
   KEY_REGEXP_HEX_DEC,
   LEN_MAX_PSK,
-  LEN_MAX_PUBLIC_KEY_RPK,
   Lwm2mSecurityConfigModels,
   Lwm2mSecurityType,
   Lwm2mSecurityTypeTranslationMap
@@ -65,7 +64,7 @@ export class DeviceCredentialsLwm2mComponent implements ControlValueAccessor, Va
   securityConfigLwM2MTypes = Object.keys(Lwm2mSecurityType);
   credentialTypeLwM2MNamesMap = Lwm2mSecurityTypeTranslationMap;
   lenMaxKeyClient = LEN_MAX_PSK;
-  allowLengthKey: number[];
+  allowLengthKey = [32, 64, LEN_MAX_PSK];
 
   private destroy$ = new Subject();
   private propagateChange = (v: any) => {};
@@ -137,13 +136,11 @@ export class DeviceCredentialsLwm2mComponent implements ControlValueAccessor, Va
         break;
       case Lwm2mSecurityType.PSK:
         this.lenMaxKeyClient = LEN_MAX_PSK;
-        this.allowLengthKey = [32, 64, LEN_MAX_PSK];
         this.setValidatorsPskRpk(mode);
         this.lwm2mConfigFormGroup.get('client.identity').enable({emitEvent: false});
         break;
       case Lwm2mSecurityType.RPK:
-        this.lenMaxKeyClient = LEN_MAX_PUBLIC_KEY_RPK;
-        this.allowLengthKey = [LEN_MAX_PUBLIC_KEY_RPK];
+        this.lenMaxKeyClient = null;
         this.setValidatorsPskRpk(mode);
         this.lwm2mConfigFormGroup.get('client.identity').disable({emitEvent: false});
         break;
@@ -160,16 +157,14 @@ export class DeviceCredentialsLwm2mComponent implements ControlValueAccessor, Va
   }
 
   private setValidatorsPskRpk = (mode: Lwm2mSecurityType): void => {
+    const keyValidators = [Validators.required, Validators.pattern(KEY_REGEXP_HEX_DEC)];
     if (mode === Lwm2mSecurityType.PSK) {
       this.lwm2mConfigFormGroup.get('client.identity').setValidators([Validators.required]);
+      keyValidators.push(this.maxLength(this.allowLengthKey));
     } else {
       this.lwm2mConfigFormGroup.get('client.identity').clearValidators();
     }
-    this.lwm2mConfigFormGroup.get('client.key').setValidators([
-        Validators.required,
-        Validators.pattern(KEY_REGEXP_HEX_DEC),
-        this.maxLength(this.allowLengthKey)
-      ]);
+    this.lwm2mConfigFormGroup.get('client.key').setValidators(keyValidators);
     this.lwm2mConfigFormGroup.get('client.key').enable({emitEvent: false});
     this.lwm2mConfigFormGroup.get('client.cert').disable({emitEvent: false});
   }
diff --git a/ui-ngx/src/app/modules/home/components/profile/device/lwm2m/lwm2m-device-config-server.component.html b/ui-ngx/src/app/modules/home/components/profile/device/lwm2m/lwm2m-device-config-server.component.html
index 3a8ac64658..b2d69c252f 100644
--- a/ui-ngx/src/app/modules/home/components/profile/device/lwm2m/lwm2m-device-config-server.component.html
+++ b/ui-ngx/src/app/modules/home/components/profile/device/lwm2m/lwm2m-device-config-server.component.html
@@ -95,24 +95,17 @@
     <mat-form-field class="mat-block">
       <mat-label>{{ 'device-profile.lwm2m.server-public-key' | translate }}</mat-label>
       <textarea matInput
-                #serverPublicKey
-                maxlength="{{maxLengthPublicKey}}"
                 cdkTextareaAutosize
                 cdkAutosizeMinRows="1"
                 cols="1" required
                 formControlName="serverPublicKey"
       ></textarea>
-      <mat-hint align="end">{{serverPublicKey.value?.length || 0}}/{{maxLengthPublicKey}}</mat-hint>
       <mat-error *ngIf="serverFormGroup.get('serverPublicKey').hasError('required')">
         {{ 'device-profile.lwm2m.server-public-key-required' | translate }}
       </mat-error>
       <mat-error *ngIf="serverFormGroup.get('serverPublicKey').hasError('pattern')">
         {{ 'device-profile.lwm2m.server-public-key-pattern' | translate }}
       </mat-error>
-      <mat-error *ngIf="serverFormGroup.get('serverPublicKey').hasError('maxlength') ||
-                serverFormGroup.get('serverPublicKey').hasError('minlength')">
-        {{ 'device-profile.lwm2m.server-public-key-length' | translate: {count: maxLengthPublicKey } }}
-      </mat-error>
     </mat-form-field>
   </div>
 </section>
diff --git a/ui-ngx/src/app/modules/home/components/profile/device/lwm2m/lwm2m-device-config-server.component.ts b/ui-ngx/src/app/modules/home/components/profile/device/lwm2m/lwm2m-device-config-server.component.ts
index d0c51ee847..63cde444ba 100644
--- a/ui-ngx/src/app/modules/home/components/profile/device/lwm2m/lwm2m-device-config-server.component.ts
+++ b/ui-ngx/src/app/modules/home/components/profile/device/lwm2m/lwm2m-device-config-server.component.ts
@@ -29,8 +29,6 @@ import {
   DEFAULT_PORT_BOOTSTRAP_NO_SEC,
   DEFAULT_PORT_SERVER_NO_SEC,
   KEY_REGEXP_HEX_DEC,
-  LEN_MAX_PUBLIC_KEY_RPK,
-  LEN_MAX_PUBLIC_KEY_X509,
   securityConfigMode,
   securityConfigModeNames,
   ServerSecurityConfig
@@ -68,7 +66,6 @@ export class Lwm2mDeviceConfigServerComponent implements OnInit, ControlValueAcc
   securityConfigLwM2MType = securityConfigMode;
   securityConfigLwM2MTypes = Object.keys(securityConfigMode);
   credentialTypeLwM2MNamesMap = securityConfigModeNames;
-  maxLengthPublicKey = LEN_MAX_PUBLIC_KEY_RPK;
   currentSecurityMode = null;
 
   @Input()
@@ -147,12 +144,10 @@ export class Lwm2mDeviceConfigServerComponent implements OnInit, ControlValueAcc
         this.clearValidators();
         break;
       case securityConfigMode.RPK:
-        this.maxLengthPublicKey = LEN_MAX_PUBLIC_KEY_RPK;
-        this.setValidators(LEN_MAX_PUBLIC_KEY_RPK);
+        this.setValidators();
         break;
       case securityConfigMode.X509:
-        this.maxLengthPublicKey = LEN_MAX_PUBLIC_KEY_X509;
-        this.setValidators(0);
+        this.setValidators();
         break;
     }
     this.serverFormGroup.get('serverPublicKey').updateValueAndValidity({emitEvent: false});
@@ -162,12 +157,10 @@ export class Lwm2mDeviceConfigServerComponent implements OnInit, ControlValueAcc
     this.serverFormGroup.get('serverPublicKey').clearValidators();
   }
 
-  private setValidators(minLengthKey: number): void {
+  private setValidators(): void {
     this.serverFormGroup.get('serverPublicKey').setValidators([
       Validators.required,
-      Validators.pattern(KEY_REGEXP_HEX_DEC),
-      Validators.minLength(minLengthKey),
-      Validators.maxLength(this.maxLengthPublicKey)
+      Validators.pattern(KEY_REGEXP_HEX_DEC)
     ]);
   }
 
diff --git a/ui-ngx/src/app/modules/home/components/profile/device/lwm2m/lwm2m-profile-config.models.ts b/ui-ngx/src/app/modules/home/components/profile/device/lwm2m/lwm2m-profile-config.models.ts
index 5e31251786..3be58c7f7f 100644
--- a/ui-ngx/src/app/modules/home/components/profile/device/lwm2m/lwm2m-profile-config.models.ts
+++ b/ui-ngx/src/app/modules/home/components/profile/device/lwm2m/lwm2m-profile-config.models.ts
@@ -34,8 +34,6 @@ export const DEFAULT_MIN_PERIOD = 1;
 export const DEFAULT_NOTIF_IF_DESIBLED = true;
 export const DEFAULT_BINDING = 'UQ';
 export const DEFAULT_BOOTSTRAP_SERVER_ACCOUNT_TIME_OUT = 0;
-export const LEN_MAX_PUBLIC_KEY_RPK = 182;
-export const LEN_MAX_PUBLIC_KEY_X509 = 3000;
 export const KEY_REGEXP_HEX_DEC = /^[-+]?[0-9A-Fa-f]+\.?[0-9A-Fa-f]*?$/;
 export const INSTANCES_ID_VALUE_MIN = 0;
 export const INSTANCES_ID_VALUE_MAX = 65535;
diff --git a/ui-ngx/src/app/shared/models/lwm2m-security-config.models.ts b/ui-ngx/src/app/shared/models/lwm2m-security-config.models.ts
index 060e1632f1..3076d5ba3c 100644
--- a/ui-ngx/src/app/shared/models/lwm2m-security-config.models.ts
+++ b/ui-ngx/src/app/shared/models/lwm2m-security-config.models.ts
@@ -16,8 +16,6 @@
 
 export const LEN_MAX_PSK = 128;
 export const LEN_MAX_PRIVATE_KEY = 134;
-export const LEN_MAX_PUBLIC_KEY_RPK = 182;
-export const LEN_MAX_PUBLIC_KEY_X509 = 3000;
 export const KEY_REGEXP_HEX_DEC = /^[-+]?[0-9A-Fa-f]+\.?[0-9A-Fa-f]*?$/;
 
 export enum Lwm2mSecurityType {
diff --git a/ui-ngx/src/assets/locale/locale.constant-cs_CZ.json b/ui-ngx/src/assets/locale/locale.constant-cs_CZ.json
index b0fc26abe2..b5a23c0150 100644
--- a/ui-ngx/src/assets/locale/locale.constant-cs_CZ.json
+++ b/ui-ngx/src/assets/locale/locale.constant-cs_CZ.json
@@ -974,7 +974,6 @@
           "client-publicKey-or-id": "Veřejný klíč nebo Id klienta",
           "client-publicKey-or-id-required": "Veřejný klíč nebo Id klienta jsou povinné.",
           "client-publicKey-or-id-pattern": "Veřejný klíč klienta nebo Id musí být v hexadecimálním formátu.",
-          "client-publicKey-or-id-length": "Veřejný klíč klienta nebo Id musí mít {{ count }} znaků.",
           "client-secret-key": "Tajný klíč klienta",
           "client-secret-key-required": "Tajný klíč klienta je povinný.",
           "client-secret-key-pattern": "Tajný klíč klienta musí být v hexadecimálním formátu.",
@@ -1301,7 +1300,6 @@
           "server-public-key": "Veřejný klíč serveru",
           "server-public-key-required": "Veřejný klíč serveru je povinný.",
           "server-public-key-pattern": "Veřejný klíč serveru musí být v hexadecimálním formátu.",
-          "server-public-key-length": "Veřejný klíč serveru musí být {{ count }} znaků.",
           "client-hold-off-time": "Čas odložení",
           "client-hold-off-time-required": "Čas odloženíje povinný.",
           "client-hold-off-time-pattern": "Čas odložení musí být kladné celé číslo.",
diff --git a/ui-ngx/src/assets/locale/locale.constant-en_US.json b/ui-ngx/src/assets/locale/locale.constant-en_US.json
index 8d1632a241..bcc13aa024 100644
--- a/ui-ngx/src/assets/locale/locale.constant-en_US.json
+++ b/ui-ngx/src/assets/locale/locale.constant-en_US.json
@@ -978,7 +978,6 @@
           "client-publicKey-or-id": "Client Public Key or Id",
           "client-publicKey-or-id-required": "Client Public Key or Id is required.",
           "client-publicKey-or-id-pattern": "Client Public Key or Id must be hexadecimal format.",
-          "client-publicKey-or-id-length": "Client Public Key or Id must be {{ count }} characters.",
           "client-secret-key": "Client Secret Key",
           "client-secret-key-required": "Client Secret Key is required.",
           "client-secret-key-pattern": "Client Secret Key must be hexadecimal format.",
@@ -1315,7 +1314,6 @@
             "server-public-key": "Server Public Key",
             "server-public-key-required": "Server Public Key is required.",
             "server-public-key-pattern": "Server Public Key must be hex decimal format.",
-            "server-public-key-length": "Server Public Key must be {{ count }} characters.",
             "client-hold-off-time": "Hold Off Time",
             "client-hold-off-time-required": "Hold Off Time is required.",
             "client-hold-off-time-pattern": "Hold Off Time must be a positive integer.",