Bad gateway on some sites

Hi

New here at cloudflare. I’ve setup a tunnel to access my docker servers running at my home. Problem is that some of them don’t run at all.

For example: I have jellyfin.vandingelen.be, http, works fine with the correct docker ip 172.x.x.x, while vikunja.vandingelen.be, also http, doesn’t work with the correct docker ip 172.x.x.x. I tried to put it on https (and setting No TLS Verify), but that doesn’t solve the problem. Gives me an Error code 502: bad gateway

What could be the problem here?