I'm intrigued as to why both these, and the Suite Numerique have chose Element / Matrix as the chat component. Every time I've tried to use Element / Matrix it has failed dismally for me and everyone else in whatever community is trialling it. Element itself was so buggy as to be unusable.
After having the same experience negative some time before Covid, I was kindly invited late last year to a homeserver of a local hackerspace and I gave it another try.
I cannot send messages to people on another homeserver (such as the obscure matrix.org one) whereas other people can, as well as some other issues which I forgot by now. Not at all usable. It was a short-lived stint and I didn't even try to enable encryption this time :(
This sounds very much along the lines of issues I had with it. It's been a while so I can't remember the exact details, but I do remember it being impossible to open a thread without the app just locking up and crashing, so people would ask important questions in a thread and nobody was ever able to reply or even read the question.
Element web and mobile have the same issue; server I'm not sure, where can I see this? I would assume the default/reference implementation but I don't know
Groups work btw, it's just private chats that cannot be initiated from either side (I have like five pending 'rooms' or something now), so it's not that one server banned the other. I just took it for typical matrix experience
it sounds like the hackspace server has been banned from inviting due to spam or something. can you share the name of the server so we can check? or mail abuse@matrix.org with the details.