I wouldn't anyway exclude that something is "wrong" or conflicting in Mikrotik settings.
In my experience (of course it depends on models) with TP-LINK access points and range extenders, they may not be the fastest or the most stable ones, but they have very limited options in setup, so making a mistake in them is less probable.
To access internet there is no actual need of true L2 bridging over wifi, everything can be at L3, and usually TP-LINK manages to deliver that.
I would suspect more DHCP conflcts/errors, and would try with static IP's for a start.
But before that keithnkmeka should post his configuration on the Mikrotik so that It can be checked if anything can be noticed that could cause the behaviour.
Instructions here: