It’s actually an older topic…
I have 3 DLink cams and via WiFi / WLAN it works with the iPhone without any problems. The timeout always occurs via the Swisscommobil network. But you try it and sometimes it suddenly works.
Interestingly, accessing the webcams works without any problems when I access the cams while roaming abroad.
It’s pretty clear to me that it has to be on the Swisscom network. There’s probably not much you can do there. All that remains is to wait and hope that Swisscom investigates the matter and solves the bug.