Deco X60 - devices not retaining connection
I've been using my Deco X60 for a few years and it's been solid and stellar. (Note: I'm not sure what hardware version I'm on; when I'm on my firmware page in a web browser it says X60(1.0) so I'm guessing V1??) My wifi network is a mix of 5GHz and 2.4GHz devices, so I can't turn 2.4 off. I have Deco set to WPA2 security.
Lately, I have been noticing that some of my devices (e.g. newer iPhones and iPads) have been falling off the wifi network. They will revert to cell service, and when I go to their Settings > Wifi, I do see my Deco wifi network listed there under My Networks, and if I touch it, it prompts me to re-enter the password (which is bizarre, since the device has the password saved). When I re-enter the password, the device connects to it properly. But then hours, or a day later, it doesn't connect, and it forces me to re-enter the password again.
This is now happening chronically across several devices. Plus, I just got a new iPhone in my house, and it completely refuses to connect to the Deco wifi. After I enter the wifi password, it just gives me the spinning progress wheel, but never connects.
What do I do? Is my Deco failing?