---> Summary
==============
- When using **OnePassDiffieHellman** signing mode in GXDLMSDirector GUI, the application throws a "Object reference not set to an instance of an object" when trying to read objects after successful connection. Additionally, the **Server keys** section in the "Secured Connections" tab cannot be expanded or scrolled to configure server certificates.
---> Environment
===============
- **GXDLMSDirector Version**: Latest (tested with v9.0.2508.2701)
- **OS**: Windows 10/11
- **Interface**: HDLC over Serial
--->Configuration Used
=====================
- **Security Suite**: Suite1
- **Security**: AuthenticationEncryption
- **Authentication**: HighECDSA
- **Signing**: OnePassDiffieHellman
---> Issue 1: Server Keys Section Not Accessible
- Description
In the "Secured Connections" tab of Device Properties, the **Server keys** section is visible but cannot be expanded or scrolled to access the Server Signing Key and Server Agreement Key configuration fields.
- Steps to Reproduce
1. Open GXDLMSDirector
2. Create a new device or edit existing device
3. Go to "Secured Connections" tab
4. Set Security Suite to "Suite1"
5. Set Signing to "OnePassDiffieHellman"
6. Try to expand or scroll to the "Server keys" section
- Expected Behavior
Should be able to configure:
- Server Signing Key
- Server Agreement Key
--->Issue 2: NullReferenceException When Reading Objects
- Description
After successfully connecting with OnePassDiffieHellman, attempting to read object "Object reference not set to an instance of an object"
-Steps to Reproduce
1. Configure device with OnePassDiffieHellman signing
2. Ensure client certificates are configured (Signing + Agreement)
3. Connect to meter (connection succeeds)
4. Try to read object
- Expected Behavior
Objects should be read successfully with decrypted values.