What to expect from a TP-Link EAP620 Access Point?

Earlier this year with the help of the fine folks at Lawrence Systems I implemented an IOT VLan in my home by upgrading our WIFI network from 3 first generation Eero devices in bridge mode to a TP-Link TL-SG2210P switch and an EAP620HD access point. My home is approximately 2500 square feet split across 3 floors vertically, metal roof, brick siding. I currently have the access point mounted at roughly the topmost logical center of the home on the 3rd floor. I’m a little disappointed in the signal strengh of the AP and am wondering if I’m experiencing (1) a natural limitation of the device, (2) a somewhat defective device, or (3) I’m experiencing interference from neighboring signals.

I’ve recently checked the channels my neighbors use and moved mine as far away as possible. I think a slight improvement was noticed from that.

Should I have purchased a different TP-Link AP? Or should I add another EAP620 and create a “mesh” situation?
Thanks so much for the guidance as I’m learning SOOO much from all your expertise!
Johnson City, TN

For better coverage you use more access points. WiFi signals can degrade quickly even in stick build buildings.