I purchased a TP-Link AC5400 in hopes to improve the reliability of my Wifi connection and have additional ports. Ever since I made the switch from a Linksys EA7500 to thisrouter, it has been nothing but headaches.

1. My phone (Samsung S9) constantly connects to 2.4 instead of 5G (never had this issue before).
2. My wifi connection (next to the router) has never been over 300 mbps (despite my internet being 1 gbps)
3. And today, I have had two wifi devices start getting speeds of ~1-20mpbs speeds (one can't even connect to the speed test website).

Anyone been able to fix this?

How is a $300 router with 7 wireless devices connected performing so much worse than a $100 router. I'm on the edge of returning this if this is the normal. 

I've also tried manually selecting channels based on Wifi Analzer, however, that only makes things slower and knocks out my Amcrest Wifi cameras...

LAN speeds are ~600-700 Mbps which isn't as close to 1Gbps as I'd expect, but thats the least of my worries..