Used TP links for about 2 years. Wired connection very stable compared to wifi and speed as good as at router

Now speed drops to almost 0Mbps. In fact Ookla tells me they is no connection

Run on wi-fi only and no issue so assume there is no external issue or router issue. When I use TP links. 3 lights working but I watch the speed drop from 50Mbps (normal) to 0 over a short period of time. 

I have 3 connectors and an separate extender and no issues for 2 years. 

Is there a lifespan on these.  

I have stopped them individually, removed the extender, used only one connection only.  No sucess.

They do feel warm,  not hot. But always felt like this. When I reboot, seems to work normally but after 1 hour speed is back to 0. It is not a data limit issue as I am well under allowance.