I bought the tp link AC2600 wifi extender as I couldn’t run an Ethernet from my router to my pc. When I first set it up and plugged in the Ethernet the internet was very unstable as if it wasn’t connected to the internet, and randomly in 2 days the Ethernet connection fixed itself and was stable. Last week I was at a different place and brought the extender with me and set it up for the new network and it worked fine instantly, now going back to the original place, the internet is again unstable when connected to the Ethernet, spiking every few seconds. My internet is good and works fine but when using the extender connected to Ethernet it isn’t working as it should. Any ideas as to why? Thanks
https://www.tp-link.com/us/support/faq/2479/
Try this option both ways and see if one works and one is flakey.
That is the only thing I can think of.