My Archer CR700 modem router frequently stops working on the 2.4 ghz band. Devices are able to connect to the access point, however all traffic on the network is not allowed. Restarting the router will fix the issue, however this solution is only temporary. I looked on the router, and it seems to disallow, and sometimes even kick off clients when their dhcp lease has expired. My lease time is currently set to one day, and I also have 5ghz enabled which seems to not be affected like the 2.4 ghz is.