My devices see the modem as a hotspot

wenijaj172

I've backed up my iPhone 11 using the modem (ZyXEL EX3501-T0) connected to Türk Telekom fiber internet, and I can't even log in to the iCloud login page while connected to Wi-Fi. In addition to all these issues, I've been experiencing Wi-Fi disconnection on all my phones as soon as I turn off the screen. I've been trying to find a solution to this problem since the day the modem was connected (about 1.5 months ago), but there are very few resources online, and the ones I've found either offer solutions I've tried before but haven't been successful, or they have no solution at all. I suspect the problem is with the modem, and I'm asking for your help.

In the picture, it says "Should apps be downloaded using cellular data?" even though I am connected to my modem.

Liba

You may need to check first whether your router has Internet service from Türk Telekom. So I think you can contact Türk Telekom to check your internet serveice and the settings of EX3501-T0.