Hello! im pretty new to networking so forgive me if i dont make that much sense

until a few weeks ago i was using my ISP provided Modem+Router+AP(all in one) and connected my Archer C6 to it so i can use it as an AP and a switch for 2 of my servers. The WIFI coverage was really great since it was in the middle of the house.

Now however i changed my setup and ditched the ISP provided box and replaced it with the Archer C6. And got myself a unmanaged(5 port gigabit) switch for the servers but since the Archer C6 was now in the corner of the house the WIFI coverage is really bad.

I was wondering if i should buy an standalone wired AP for the middle of the house that can connect to the 5 port switch or something else. And i also want to use One mesh or Easy mesh

Extra info:

getting 200-210 Mbs from ISP

When Archer C6 was in the middle of the house worst place had a 2.4GHZ/5GHZ connection that was around 25-50Mbs which is mostly enough it would be better if it was higher

Also another question if i were to transfer files locally to my servers through the gigabit switch the wifi will be effected right?