To be honest I was thinking yesterday a 2.4 radio was on the way out but when I changed the least time and the problems stopped I thought it could be a coincidence and still a radio might be on the way out. But at the same time hoping it was just a config error that hadn't materialised because of the 90 day lease.I doubt you have a settings issue. You have a lot of (6) strong radios in one place (probably too many); and AC86Us have a history of hardware failure, the 2.4 radio and a power circuit... both faults can cause strange behaviors that will not go away. Be prepared to isolate and remove suspect units from your network while troubleshooting or else you'll be chasing issues for some time.
A WiFi analyzer app can help see unstable radio signals bouncing in and out.
OE
Thanks for the advice, I'm going to have a look at suitable upgrades in the event a router needs replaced. I'll also have a look at the WiFi apps to see if I can see any signals bouncing in and out. Thanks again