I've recently switched internet provider, and all of a sudden my powerlines won't work as well as before. I've tried everything from resetting to buy a new set in case the old set was broken but the results are all the same: my PC's download speed goes between 2-3mbps to, from time to time, 8-9mbps. My upload speed is good, always between 18 and 20mbps. Wifi and modem are working fine, reaching 90mbps download speed and the same upload speed.
I can't use a wifi repeater cause my house is the old type with thick walls and on two floors so the signal is very poor, especially on a side of the floor and, even though the electrical wiring is old, it's never been a problem since now.
The only thing that really changed is that even though I have FTTC, the provider had me install an adsl filter box now.
(this thing here)
I contacted TP-Link and the provider to ask if there's any compatibility issues but they both assured me there are none.
Does any of you know what's the problem and how to fix this?