Configure SNMP and wait until next time internet/wireless is affected.

Is there any thing in particular I should look for?

CPU usage/memory usage/all errors

I think this is purely a symptom of this device. The firmware is ancient and the product is EOL. I do not see us getting any updates or help on the issue. I have two of these devices and have the same ritual.

If you do find a solution, please post back.

Same thing on mine... Support is clueless, they'll only go as far as telling you to update firmware and reset to factory defaults.

Unfortunately, the lack of any firmware updates and no communication (yes I am a TP-Link reseller partner and my rep was no help on this either) on whether they would EVER becoming forced us to leave TP-LINK for an alternative vendor.

The firmware on all the "business class" routers is ancient (far over a year old).

It's a shame as the TP-Link products have some nice features and a good price point but are just very unreliable/stable.
I even have issues with some of their smart switches needing rebooting on a regular basis (these are slowly being replaced as well) - a problem my Cisco Small Business or Araknis products never have..

Yes I have called support, posted here, etc. The problems are the devices (specifically firmware). It is easy to identify (for example on some models you cannot even do a complex password (i.e. use special characters).

This is just my opinion, take and use it as you see fit.