my self-hosted instance behind Traefik (https://bitwarden.mydomain.com) has been running fine for over a year, even now the Firefox extension and Android app work. But the Web UI is having issues - after entering my email and master password I get the following error: NetworkError when attempting to fetch resource.
Are you using the vaultwarden/server image for self-hosting? Or do you use a self-built / third-party web-vault? Also do you have any firefox extensions installed that might be interfering? Or did you change the content security policy? Can you check the browser console for any logs?