Well then, Mister Arch, you have not tried a TJW's client lately.
Not that I have.
Well, yes, the TJW client can use cl_guidserveruniq.
Sayer, are you on a university connection or something?
Any kind of shared connection may have packet detectors that stop packets from the master server. Try connecting directly to an IP with /connect.
As for the screenshots and demos, do you mean you can not view them with the Oticz HUD viewers?
If so, that's a pretty normal issue when transferring installations and their settings, or, it is for me.
Try uninstalling and reinstalling the HUD, if I recall, the uninstall cfg will reset all cvars related to the menu files, and should fix your issue.