Verification Error on self-hosted Kontalk server

Hey there,

So, I guess you’re using the xmppserver-docker repository without changes to the Dockerfiles .
What’s your version of Docker?

Yep, no changes whatsoever.
I’m using Docker version 18.09.6, build 481bc77156.
I further tried setting up the server on my local machine (same host environment as the server), the instance doesn’t crash but only allows a single registration on rebuild/restart, the subsequent registrations return the 'Verification code refused" error.
Here is p ofart the server logs

On a debian server I get an error similar to this
A more powerful instance doesn’t really help in my case.