I'm not sure if this is the same issue as the "Read This" post but I'm going to post it anyway.
For the last couple of weeks I've had problems with WiFi dropping out for various devices. Problem seems to be mainly with 5ghz however my partner has said that 2.4ghz has started having issues in the last few days (on her work laptop).
My personal laptop will not maintain a connection to 5ghz. It usually drops out after about 10 mins and requires the router to be restarted. Then I get a further 10 mins before another drop out. Because of this, I've had to connect to 2.4ghz which has relatively stable connection however the download speed is around 50mbs whereas 5ghz is about 110mbs.
When the laptop was initially dropping out there were no problems with other devices however all three Amazon Echos I own all stopped connecting to 5ghz and were unable to reconnect after re-setting them up. I've also noticed issues with various Android devices on both 2.4 and 5ghz. PS4 and LG Smart TV remain unaffected as far as I can tell. I also have a wired PC which also doesn't seem to have any issues.
Dunno if its relevant to your issues but... The SH2 is known to develop a fault as it ages whereby it will revert its security setting from the usual WPA down to WEP and that means devices wont connect. Have you noticed any "non-secure" type error messages ?
-------------------- John --------------------
My services: HD TV on VIP (+ Sky Sports & Movies & BT sport), x3 V6 boxes (1 wired 2 WiFi,) SH2 in modem mode with Airport Extreme Router. On VIVID200, Talk Anytime Phone, x2 Mobile SIM only iPhones.