ArcherC5400X v1.0 NOT the Archer A2300 (no option)

I bought the TP-Link Archer AC5400X gaming router and TP-Link T1600G-52TS JetStream 48-Port Gigabit Smart Switch with 4 SFP Slots smart switch as a upgrade. the existing hardware worked fine without issues, but I have upgraded my internet package and needed to achieve higher bandwidth rates. I have tested the new Arris SB8200 modem that I have had for a while. I plugged right into the cable modem and everything works fine. when i plug into the router is when everything slows down. I tried bypassing the switch and that did not help. There is something wrong with the router and I cannot figure it out.