VNC console not working

The VNC console isn’t working

Expected outcome:
The VNC console is working

Foreman and Proxy versions:

Foreman and Proxy plugin versions: 3.3.0
foreman_dhcp_browser 0.0.8
foreman_kubevirt 0.1.9
foreman_memcache 0.1.1
foreman_puppet 4.0.1
foreman_templates 9.3.0
foreman_vault 1.1.0
puppetdb_foreman 5.0.0

BMC 3.3.0
DHCP 3.3.0
HTTPBoot 3.3.0
Registration 3.3.0
Reports n/a
TFTP 3.3.0
Templates 3.3.0

Distribution and version:
Ubuntu 20.04

Other relevant data:
The certificates are properly installed and a openssl connect against the websocket port passes the certificate validation.

The debug log below doesn’t seem to give useful outcome, at least for me.

2022-06-28T11:13:43 [I|app|70202a05] Started GET "/hosts/vm.tld/console" form.y.i.p at 2022-06-28 11:13:43 +0000
2022-06-28T11:13:43 [D|app|70202a05] Cache read: _session_id:2::48730520faca09b501df8659f3f7dc155f50b58c35dbe8f6f521a4d79a98f321
2022-06-28T11:13:43 [I|app|70202a05] Processing by HostsController#console as HTML
2022-06-28T11:13:43 [I|app|70202a05]   Parameters: {"id"=>"vm.tld"}
2022-06-28T11:13:43 [D|app|70202a05] Cache delete: views/tabs_and_title_records-9
2022-06-28T11:13:43 [D|tax|70202a05] Current location set to none
2022-06-28T11:13:43 [D|tax|70202a05] Current organization set to none
2022-06-28T11:13:43 [D|app|70202a05] Created libvirt connection 211340: qemu+ssh://foremanlibvirt@kvm.tld/system
2022-06-28T11:13:43 [D|app|70202a05] Starting VNC Proxy: /usr/share/foreman/extras/noVNC/ --daemon --idle-timeout=120 --timeout=120 5912 kvm.tld:5900 --cert /path/fullchain.pem --key /path/key.pem
2022-06-28T11:13:44 [D|app|70202a05] VNCProxy Error: WebSocket server settings:
 70202a05 | 
2022-06-28T11:13:44 [D|app|70202a05] VNCProxy Error:   - Listen on :5912
 70202a05 | 
2022-06-28T11:13:44 [D|app|70202a05] VNCProxy Error:   - Flash security policy server
 70202a05 | 
2022-06-28T11:13:44 [D|app|70202a05] VNCProxy Error:   - SSL/TLS support
 70202a05 | 
2022-06-28T11:13:44 [D|app|70202a05] VNCProxy Error:   - Backgrounding (daemon)
 70202a05 | 
2022-06-28T11:13:44 [I|app|70202a05]   Rendering hosts/console/vnc.html.erb within layouts/application
2022-06-28T11:13:44 [I|app|70202a05]   Rendered hosts/console/vnc.html.erb within layouts/application (Duration: 2.7ms | Allocations: 918)
2022-06-28T11:13:44 [I|app|70202a05]   Rendered layouts/_application_content.html.erb (Duration: 1.4ms | Allocations: 691)
2022-06-28T11:13:44 [I|app|70202a05]   Rendering layouts/base.html.erb
2022-06-28T11:13:44 [D|app|70202a05] Cache read: views/tabs_and_title_records-9 ({:skip_digest=>true})
2022-06-28T11:13:44 [D|app|70202a05] Cache write: views/tabs_and_title_records-9 ({:skip_digest=>true})
2022-06-28T11:13:44 [I|app|70202a05]   Rendered layouts/base.html.erb (Duration: 38.7ms | Allocations: 34142)
2022-06-28T11:13:44 [I|app|70202a05] Completed 200 OK in 1135ms (Views: 46.2ms | ActiveRecord: 2.9ms | Allocations: 200246)
2022-06-28T11:13:44 [D|app|70202a05] Terminating libvirt connection 211340: libvirt_connection_qemu+ssh://foremanlibvirt@kvm.tld/system
2022-06-28T11:13:44 [D|app|70202a05] Cache write: _session_id:2::48730520faca09b501df8659f3f7dc155f50b58c35dbe8f6f521a4d79a98f321 ({:expires_in=>86400})

Any hints how to further debug this problem?

Thanks in advance