[2.0.14] "server not responding" after UserVerificationMissing

[Sonokort]

Hi there,

I'm the only one on our server that gets kicked after a few minutes from the server after the "Server not responding" message.
The progress bar alwasys goes through to the end, not once was my game able to reconnect.
After getting disconnected I can reconnect immediately without issues and get kicked again after approximately 1-5 Minutes of active play.
This problem started occuring just 2 days ago, it didnt happend once for the first 25-ish hours of gameplay.
Furthermore, I already played on a similar MP server (same host) about a year ago with the same PC, Router and Internet provider and had no issues.

My Internet connection should be fine. Multiple speedtest gave me sufficent up- and download rates (4 MB down, 2 MB up) and a ping below 50ms. Everytime I got kicked the game showed a latency below 20 ticks (most cases around 7). Portforwarding for Factorio is active and set to UDP.

A Firewall exception for Factory was already in place before I started playing on this server.
I tried uninstalling the game through steam, even deleted the %appdata% folder, downloaded it from the factorio website itself to bypass steam, and reinstalled and ran it as an administrator. Nothing Changed.

The disconnects dont coincide with the autosaves from the server.
The server is hosted externally through nitrado.net, We dont use any mods.

Player log and Serverlog are attached.
The Serverlog states that the connection was refused due to "UserVerificationMissing", but I bought the Maingame from Steam and the DLC from the official website. Nevertheless we tried to change the server config file and changed UserVerification from true to false, but the problem still persisted.

I'm very thankful for any tips or ideas to further troubleshoot or resolve this.