I've got 1000 mb/s internet connection and on main router high internet speed. Because we live in a big house with thick walls, we have a TP-link Deco mesh system for wifi. Main deco is a Deco P9 with PLC, with a direct cable connection to main router. Internet speed on main deco is good.

Connected to main Deco are 3 P9's (all with PLC) and 2 X10's (without PLC). These other Deco's are very unstable with internet speeds varying between 1 - 250 mb/s, and very often one or several deco's lose all internet connection. The P9's (with PLC) very often don't use their PLC function.

I've tried every standard solution, reset the system very often, moved the deco's, tested the system with fewer deco's (I started with 3 in total, but since connection was still *****, I added more deco's step by step), tried to improve results by linking 2 deco's with a cable connection.......

Please help, because it is very frustrating to have such an expensive system and still 1955-style internet connection.