My isp(Unifi) promises 800mbps using wired connection. My speedtest shows 700-750 mbps which is good enough for me but after a few hours the speedtest can only go up to 250mbps and just stay at that level almost like it is being capped/throttled. It will only go back up to 700++mbps once i turn the router on and off which only lasts for a few hours and then its back to being limited to 250mbps. I checked with unifi technicians and they check their side and informed me that there is no fault from their side. They also tried using their own router and changed the modem to a new one without problems and concluded that the problem is with my tp-link router. I have contacted tp-link about this issue and they emailed me a firmware to fix this problem but when i tried to upgrade the firmware from settings, it shows a message "unable to upgrade". What do i do next? How do i upgrade to this firmware? Should i request an RMA? Please advise.