This is the second or third time I've experienced this issue in about 2 months, but I've owned and used the powerline adapter (TL-PA9020-KIT) for around 16 months, which is necessary for providing a stable connection to the first floor of my home (very unreliable wifi).

Here's my setup:

Everything upstairs (several PCs, Sky Q Mini and powerline adapter 1) is connected to a Netgear switch, which is connected to my Sky Q router (router simply provides internet, no additional devices plugged into router. Etehernet setting is set to Fast Ethernet)

Downstairs, everything else (Smart TV and Sky Q box) are plugged into powerline adapter 2.

The last 2 times I've experienced this (the last time earlier today) I've noticed it before turning on the PC or browsing online, as the playback on my Sky Q Mini (which streams over the LAN, connected directly to the switch) becomes super choppy.

I try an internet speed test on my phone (via wifi) and everything seems good.

I then try an internet speed test on any wired device and I get terrible results.

Figuring it's some sort of interference, I remove everything from my LAN switch so it is only connected to my PC and my router, try the test again from my PC and get full speeds.

I then plug my devices in one by one, testing my internet speed.

Both times this has happened, removing my TP-Link Powerline adapter from the network has singularly resolved the issue.

Switching off the TP-Link device, letting it rest for a bit, then turning it back on, also resolves the issue, however I did notice the moment after I switched it on it caused my PC's connection to drop momentarily.

I have manually assigned IP addresses to all the essential gear on my network so the issue I don't think is due to IP address conflict (the reason I manually assigned IP Addresses however was due to an IP address conflict caused by my Sky Q box, causing all kinds of havoc with my network)

I've diagnosed the issue down to the powerline adapter, but I acknowledge that the issue may also lie with my Netgear switch (unlikely) or my Sky Q router (likely).

Is this a common issue? What can I try to prevent this happening again?