Adding second device fails - "last error not set"

[punkt-x]

• Operating System (Linux/Mac/Windows/iOS/Android): Win11
• Delta Chat Version: 1.48.0
• Expected behavior: Adding Win PC as second device (main device is an android phone)
• Actual behavior: after QR scan the process of adding starts on both devices. After 30 seconds the android phone gives an error message: "Sending Error:
• Steps to reproduce the problem: I repeated the process several times, firewall is deactivated for delta chat, manual addition via backup file of the delta profile fails as well
• Screenshots: ---
• Logs:

[nicodh]

Can you provide a log after trying?
From the top menu:
View -> Developer -> Open Current Logfile

What do you mean with "last error not set" in the issue title? Where is that shown?