How to configure apache proxy to also support websockets for /-/cable

Self-hosted GitLab 15.8 on Ubuntu with successful Apache proxy running for years.

But the browser console is full of failed requests to wss://gitlab.example.com/-/cable triggered by action_cable.js line 197

Wasn't able to find any working configuration for that to work and wonder if the templates for apache in this repository could be adjusted for that?