SSL Websocket can’t establish a connection since today

I wish all readers Merry Christmas and nice gifts,
My christmas gift was a connection error with my websocket project.

Backend is a Ubuntu Linux virtual instance with an apache server and python 3.10 with websockets as lib.
Frontend is a Ubuntu Linux virtual instance with an apache server and a builded webgl appliance.

Since today i cant create a connection with the same code.
JS:

const socket = new WebSocket("wss://domain:port");
..

Python:

...
ssl_context = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
ssl_context.load_cert_chain(certfile="./cert.pem", keyfile="./privkey.pem")


async def main():
    async with websockets.serve(server, "", port, ssl=ssl_context):
        await asyncio.Future()  # run forever

asyncio.run(main())

The frontend is on a diferent webserver as the websocket server.
I can create a connection with ws. The port is open (i checked it in my cloud overview and over ufw and nmap)
I have ssl certs for my frontend and backend with differenz domains/ips created over lets encrypt and these are valid today.

Have anybody an idea why this sucks up today ?

What i did:
Restarted my pc
Restarted my cloud pc
Drank a beer
Reseted my code to a date who i know 1oo% that was working
Tested it without ssl

Expected result: connection can created over ssl..