Problem using special characters on the SwissGerman keyboard

[Hendrik Jan Boven <he...@visana.ch>]

Hi there this is my first post here to this mailing list so please be patient if I have misunderstood something.

I'm using Guecamole for remote access RDP & SSL connection into my HomeLab and almost all is working just fine.
The installation is using the official Docker images with Mariadb and is behing an nginx reverseproxy running in Docker as well.

When I connect to a RDP host I get a working connection and almost all is fine just the keyboard is giving me problems.
Both the connecting client and the RDP Host have the SwissGerman keyboard Layout. (https://en.wikipedia.org/wiki/QWERTZ#Swiss_(German,_French,_Italian,_Romansh),_Liechtenstein,_Luxembourg)

When I started typing I noticed some reproducible problem using the special characters. If I start typing the keys from the top character row from left to right I should get:
qwertzuiopü

However I do get:
qwertzuiopüüüüüüüüüüüüüüüüüü  and I have to press any other key or backspace or so to stop the repeated üüüüü from coming.

If I immediately try again to do the same I just get:
qwertzuiop  and the ü does not work

After a minute or so of waiting I can type the ü again and get it to show up. But that trick works only once or twice then stops working completely and from there on I have to use copy paste to get these characters.

The same happens to be the case with the second line of the keyboard asdfghjklöä where the ö and ä show exactly the same behavior.

If I use the same Client locally to establish a RDP Session this behavior is absent.

Does anybody have any ideas what might be the case? Is this a bug or have I overseen some Configuration setting?

Regards,
Henk