@Onsku29
This could be one of two reasons, sadly neither are "fixable" and require newer hardware.
1. The LAN Port on the 4010 is limited to 100mbps, in non duplex this would be 50mbps. If you internet is faster than 100mbps (which is quite common now) then that LAN port will be a bottleneck
2. Plug Speed vs Real Speed. Plug speeds, like WiFi speeds are always the theoretical maximum and actual transfere rates will vary. If you plugs are reading connections of 250mbps between the plugs (on the app) then assume the real speeds to be around 40-60% of that so 100-125mbps at best.
Honestly.. these are quite old plugs and run the AC1 standard of Powerline (2 wires) the AC2 standard (3 wires) is much faster and more reliable. If you have an internet speed over 100mbps then you really should be looking for AC2 standard plugs in the 1000mbps speed range, something like the 7517
IMHO the 4010 model plugs are only good for internet speeds up to ~60mbps, any faster you will need the newer AC2 models.