Cannot login - Riot/Matrix

Brief summary:
When trying to sign in into Disroot’s homserver, I receive the following error:

Error: Problem communicating with the given homeserver. (M_UNKNOWN)

I tried using variety of clients, effect is always the same.

Base on similar issue, this might be related to some server-side problems, e.g.

It seems that there’s no such problem anymore, things are working fine.