Testclient bailing with Received: Authentication timeout

I have setup (perhaps correct) the notify_push service. The clients are (seemingly) not recieving the 'notification'. However the test_client bails (instantly) with a timeout...

Found push server at wss://nextcloud.beetjevreemd.nl/push/ws
Received: Authentication timeout
Error: 
  0: IO error: CloseNotify alert received
  1: CloseNotify alert received

Location:
  test_client/src/main.rs:39

 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ BACKTRACE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
  1: color_eyre::config::EyreHook::into_eyre_hook::{{closure}}::h9efefbf195760dbe
     at <unknown source file>:<unknown line>
  2: test_client::main::hbfaff217f5a6f51d
     at <unknown source file>:<unknown line>
  3: std::sys_common::backtrace::__rust_begin_short_backtrace::hd2d2d38788a19c55
     at <unknown source file>:<unknown line>
  4: main<unknown>
     at <unknown source file>:<unknown line>

Run with COLORBT_SHOW_HIDDEN=1 environment variable to disable frame filtering.

real	0m2,533s
user	0m0,005s
sys	0m0,011s

Start with test_client/src/main.rs:39 and reproduce the reported authentication timeout against the listed push-server endpoint. Trace the test client's authentication exchange and verify that it completes and can receive a notification without the connection closing.