Microsoft Word extension fails to connect to custom server

Development
1

Hello

I have LT running locally in home server. It is running on headless server 192.168.1.1 on port 8010, and it responds nicely to all LAN hosts requesting at http://192.168.1.1:8010/v2/check.

Browser extensions and LibreOffice also works nicely on all LAN hosts connecting to my custom server, but MS Word extension does not work. It does not even try to connect to my server.

If I set http://192.168.1.1:8010/v2 in MS Word extension’s custom server field, I get http://192.168.1.1:8010/v2: a network error occurred. Please check your Internet connection on “check document” action, but checking via Wireshark/tcpdump on server shows zero traffic towards it, via any port. So the problem is not even a protocol/path/connection one, as TCP connection is not even attempted to the server.

I’ve tried different creative ways to set the custom URL like:
— 192.168.1.1:8010
— 192.168.1.1:8010/v2
— http://192.168.1.1
… and so on. No connection is visible on server connection log / tcpdump

Please mind that on very same host running MS Word, the browser extension works perfectly fine with custom server. This should exclude local firewall related concerns.

I’ll move my diagnostic on the Windows client, I’ll post again if I end up with something with it.

2

Does it work with https://api.languagetool.org/v2? Then the issue might be that MS Word only accepts https connections.

3

I had my opening post in revision due to being the first one, so I had no possibility to quickly give feedback about the HTTP vs HTTPS findings.

I can confirm that the MS Word only accepts HTTPS endpoints, no matter if the destination lives in private network space.

To make it work, I had to put LT service behind TLS terminator with let’s encrypt certificate backed by DNS certbot auth to work with private addresses. I have no idea if it would work with self-signed certificate, too.

Surely this is an overkill solution for a simple problem. Not sure if this limitation is imposed by MS Word or is implemented in the LT Word extension, but surely it makes quite hard to have LT running privately on custom server while using MS Word.