I have 3x Deco XE75 Pro located one in Semi-Basement Garage wired In from Service Provider modem (ARRIS - 8017) (1Gbps Download x 60Mbps Upload) and out to a switch TL-SG1008D, 2nd Deco XE75 Pro is located to 2nd Floor Wired to the Semi-basement Garage Switch and 3rd Deco XE75 Pro is located in the Washroom 3rd Floor Wired to the Semi-basement Garage Switch.

Unfortunately Wireless Signal none of them reach my combined Kitchen & Living Room Located in the other end of the 2nd Floor and under the Washroom 3rd Floor.

Previously I configured the network by adding a "Netgear Nighthawk X6S AC3000 - EX8000" as an extender, where wireless Download Speed in the Kitchen & Living room was reaching 250Mbps and Upload 55Mbps. BUT unfortunately the Connection of the EX8000 was very unstable where I had to restart the Ex8000 almost every day.

Current configuration I removed the EX8000, while on the 2nd Deco I added a Powerline "Solwise PL-1200AV2" and connected the other Powerline in the Kitchen, Outlet from Powerline into "Netgear Nighthawk X6 AC2200 - EX7700" and connection became very stable. BUT unfortunately the wireless download speed is much slower than Previous configuration, having Download Speed of 35Mbps and upload speed 57Mbps.

Note that the 1st Deco XE75 Pro IP goes with xxx.xxx.68.1 and 2nd & 3rd Deco XE75 Pro IP goes with xxx.xxx.71.xxx, while I tried to use my previous devices.

Note also that electricity is 3 Phase.

Could someone please advise what is the problem or configuration to manage to increase the speed in the Kitchen / Living Room.

Thanks.