error sending answer to client trough broker: error sending answer to broker: remote returned status code 400

On 05.sep.2024 04:15 (UTC +2) my snowflake proxies could no longer establish new connections and it looks like all previous connections stopped as well. One snowflake proxy with debug logging enabled reported the logs shown in the screenshot.

After a restart of the proxies, the NAT test resulted in "NAT type= restricted" which is not true. No restart of either router or server solved the problem. At the time, I was running snowflake-proxy 2.9.2 (6d2011de)

During the troubleshooting I upgraded to snowflake-proxy 2.9.2 (ec9476e5) which also didnt solve the issue.

Only after I disconnected and reconnected the modem to grab a new ip address everything started working again.