Why can't I access the WebUI from an Android device in the same WiFi net?

[eagle38106]

Hi,

i can set up a brand new Shelly 1PM via Shelly Smart Control app on my tablet and attach it to my WiFi. No other settings made. If I type its IP-address in a browser on my PC, I'm "in" at once and could do anything I want to.

But if I type in the very same IP-address in any browser on my smartphone or tablet - which is in the same WiFi net as the Shelly, I do only get an error message like "Unable to connect" on the tablet in FireFox or "This site can't be reached" in Vivaldi.

However, if I disable WiFi on my smartphone and active a VPN connection via LTE into my home, I can access the shelly.

What goes wrong? What am I missing?

Cheers.

Edited November 7 by eagle38106

[eagle38106]

I've just discovered, that I can access the WebUI via LAN connected Desktop-PC, but not via WiFi connected laptop.

[wimb]

PC has a cable ? If yes then probably the WiFi has the Client Isolation enabled. 

[eagle38106]

No, in the router, the box is checked, that "active WiFi member can communicate amongst each other".

A ping from the WiFi connected laptop to the tablet on WiFi works perfect.

[Heinz]

when you are connected to the network via lan what is your Ip address that you get and then the same when you connect to the wifi. 

With out knowing the Ip address it would be hard to really know why I think it could be a IP address issue when connecting to the network. 
The best method to test this on the laptop is cmd. Ipconfig to check the ipaddress and then ping the device with Ping <ipaddress> -t 

is suspect that when the wifi is connected it might be that its on a other network or Ipaddress range 

[eagle38106]

After a router (FRITZ!Box 5590 with OS 8.00) reboot, the situation remained unchanged. But after I activated a VPN on my smartphone into my network while the WiFi on my smartphone was still active, it has triggered something inside the router and it worked at once on all WiFi connected computers. Smartphone, tablet, laptop. Just like that. A friend suggested a f***** routing table. I do hope this won't happen again.