I don't have a Chromecast. I've returned my router and bought Archer c7. Now everything works fine (the same configuration, the same connected devices)

Archer C1200 v2.0, firmware 2.0.0 Build 20170206 rel.46023 (EU) and I have exactly the same problem several times a day. I cannot reconnect my devices (2 android phones, 2 laptops - 5GHz and printer...