C3700 Loose internet connection on some devices while not others. Local network connection still OK

[seronil2]

Firmware V1.0.0.42_1.0.33

Sometimes (a couple time a day) then we lost connection to internet.
I can lost internet on one unit (Wi-Fi) but other units is working.

When I log into the router then it says the internet is Good. (or course other units is still working)
In the rounter I can see my phone is connected, but I don't have internet access from the phone.

The phones can be SamSung S8, Iphone 7, Iphone SE, Ipads... it is same for all.
Like the router doesn't route the traffic for all units
OK. I have found a workaround if I go to Basic / Wireless and press Apply, then it begin to work again after some seconds for all units.

I don't do any changes, just press Apply

I have between 10-15 units connected to the router.

Today we also found a new issue for first time, Insternet was lost on my wifes laptop, then she remove the cable and it begin to work.

This was the first time the cable didn't work

What can be wrong?
Router address is 192.168.1.1
I have DHCP 192.168.1.2 - 192.168.1.254

[jjczon]

Have the same issue with my Samsung S7 edge.
Have read it could be an IPv6 issue. Advise was to disable IPv6 on the router, unfortunate so far haven't found a way to do it.