PowerLine TP-Link Problem, High latency

[kostasrdg]

Hello to everyone, the last days i have a weird problem with my powerline. I used it 1year+ in that specific room and that week i get like 2000ms from evening until late night hours. It's like my network is overloaded but it's not. My internet isn't the best as it reaches 5Mbps to both PCs
(1.connected with router, 2.connected with powerline). At the morning my connection speed is normal around 5Mbps but around evening drops to MAX 1Mbps (mostly 0.50Mbps-). I have no idea what it may cause that problem since i use that powerline with the same connection and everything like more than a year and suddenly that problem occurs.
Let me know if you need more details and thank you in advance!

 

[getochkn]

Any new appliances added in the house. Is it a house or apartment? Any new device at all plugged in?

 

[kostasrdg]

It's a house around 70-80m2.
Everything is as usual as before the problem on both rooms that there are the powelines (the one with router and on the other with the PC that need the Powerline).
Near modem there are 2 power strips the 1 has safety sockets and has only the 1 TPlink machine that is connected on router and 1 more power strip connected on the safety one. The 2nd TPlink machine at plugged connected to the wall, but i had no problem with the 1st one before.