Do (internet) clients need access to webinterface for auto update?

Maybe it’s a stupid question. But it’s not clearly stated in the documentation, and I don’t want to wait for the next client update to test it out myself ;-).
But do clients need access to the urbackup web-interface to auto update the client? Or is the update send over the usual backup link? The Documentation uses the word “send” but doesn’t clarify it further.

No it’s done via the usual backup link.