adding the bool:ignore-ssl-errors=true to my jabber.ccc.de account was all it needed...actually putting the string:server foo there in addition broke it again, does that check out with you guys?

I don't have the "server" string on my desktop, either. Settings on my desktop are:

(uint) port = 5223
(bool) old-ssl = true
(string) resource = Desktop
(string) account = blabla@jabber.ccc.de
(bool) ignore-ssl-errors = true

On the Jolla phone it now is:

(uint) port = 5223
(bool) old-ssl = true
(string) account = blabla@jabber.ccc.de
(bool) ignore-ssl-errors = true

The port number is probably not necessary, don't know why I changed it to 5223. I guess it's old-ssl and/or ignore-ssl-errors that made the difference.

what does the old-ssl do?

Why would you need all those settings though? Are those servers having problems with proper SSL usage, or it's some kind of Telepathy issue?

I think it's because jabber.ccc.de is self-certified, so it doesn't check out against the usual certification entities. But hey, I just own a Jolla, I have no idea about how computers talk to each other.

Nothing. It won't be added to new accounts anymore in a future update.

Does anyone know how I can change the priority?

I see on my server that my jolla phone registers with priority 0, but I want the same priority as my other clients.

Bad error reporting is known. There has been some work done on exposing more options to the UI, but I don't have any idea when it will be available for you yet.

any infos about file transfer , like pic, videos, files... ?

No news at this time.