Sometimes coverage is better than a single router, even if it's faster. 5Ghz degrades quickly over distance. Assuming that may be the case here as the old one looks better on paper.
What router did you go with? As far as I know, proper TP-Link mesh only works if you have the controller. The AP's will still work without, but it facilitates roaming and band-steering. iPhones and some other devices like to hold on despite signal strength, but everything else seamlessly moves to the stronger signal.
I quickly threw this together when we moved in so I could work out of the basement during reno. ER-605, OC-200, 24 port PoE switch, 2x EAP-620HD. Just need to clean it up some day, or make it look pro with a patch panel.
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