Etherpad constantly reconnecting / session id unknown

[GrooveOperator]

Hey together,
we are using etherpad-lite on an apache 2.4.18 and experiencing several reconnection attempts per minute. Etherpad shows this message, followed by "Connected":

The connection to the websocket is realized via a reverse proxy, set in the Apache configuration, that redirects the urls to the port etherpad is running. A network analysis showed that etherpad is having trouble with validating the session id. The request structure is always as followed:

The selected GET-Request comes back with a "Code:1 Session Id unknown". Etherpad is then requesting a new sid and the process repeats.

The Server Log is showing no suspicious errors other than access logs, so I also tried debugging via browser console which gave me the following output:

This thread might be related but there is no answer: #3078.
Does anybody know what is going wrong here?

[GrooveOperator]

To whom it may concern: Found the error myself, reason was a mistake in the configuration of my reverse proxy. I used the wrong protocol to access the websocket (had to use "wss:" via ssl instead of "ws:")