All my devices lose Internet connection
Note:  This answer can be applied to any ISP supplied router; it's not limited to the model identified in the question.

The fact that all your devices are losing Internet at the same time narrows the potential failures down significantly and rules out a problem with your Macs and iOS devices.

The issue is down to the "router" that your provider issued you and there are two potential issues:


The WiFi radio could be faulty
The router is faulty


To test out which is the issue, connect your iMac or MacBook Pro directly to the router via Ethernet cable into one of the LAN ports (see below).  Make sure you turn off your wireless on that device.



If the problem remains, it's with the router's connection to your service provider.

If the problem goes away on the Ethernet connected device, the WiFi radio is at fault and the router needs to be replaced.  However, I personally, wouldn't depend on a service provider supplied router.  I would get one that I have control over and just put their router in "bridge mode."