Try connecting a device direct to the CM400 modem? Don't forget to power cycle it after. Sounds like a router problem to me.
What model TP-Link did you go with and how far away are you from it? Also, are you connecting at 2.4 or 5Ghz? Since you had a mesh network before and now it sounds like you don't, I wonder if wifi signal strength is playing a role. Last, have you tested a wired connection to the router?
tp-link AX3000 (Archer AX50) which was still in the box from when I bought it just before the Eero system. After everything is back together, I do think the speed is ok, but yes a little weak wifi at the back corner of the house. Because of the ethernet situation during the failure period, I switched the Rokus and the TIVOs to wifi, so that has added a little load, but they seem ok. Most of my devices are older, so only two or so can use 5Ghz.
I thought at first the ethernet was 'a beat' slower, but maybe not. According to the Cox speed test, I'm at 286/12 which seems adequate for my use.
Thanks again for you help.
