You could well be overloading it. It is working as a Modem, Router, Switch and WAP. My preference is to try and separate the various functions.
As a minimum, leave the TP-link running as modem and router and then feed that into a small 16 port switch. Install a decent pair of WAPs which connect back to the switch. All traffic is then handled by the switch and only traffic to/from the outside world will go via the link to the router and modem.
M H C
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