I set up my LanguageTool server using this docker container https://github.com/silvio/docker-languagetool .
I tunnel this traffic through an nginx reverse-proxy which encrypts the traffic and exposes it to port 443 on my server. Now, when I add this server as custom server in the firefox extension, it does not work.
Instead, it tries to correct the text for a few seconds before erroring out:
Sorry, something went wrong while checking your text (400)
Did I configure something wrong?