Sorry i didn't realize you meant wired.
You have a HUUUUGE amount of stuff to consider.
- Your expectations with your ISP.
My cable ISP provider does not give me advertised speeds but close to it though.
If i were you i would break it down.. are you running 10/100 or Gigabit ?
I asked you what your hardware supports wired or not you need to know this info.
I would try different cables to be sure too.. i have had hundreds of pounds of cables and done my homework.
Cat cables and Cat-E or not the same.. make sure you are using CAT-e
Cable length being too long can degrade things too if excessively long.. although this is rarely a problem.
Have you verified for sure what you are supposed to be getting then tested it ?
For 15 years i have used SpeakEasy.net (Seattle) to test my speeds.
Sometimes they change the packages etc so make sure you know what the ISP claims
You mentioned VPN ?
I coded my own file sharing program mod a dozen years ago.. so i know file sharing
i don't use VPN's but i know they are a proxy so running your Torrent etc through a VPN can slow you down.
It's an extra hoop to jump through..
Throttling is an issue too but do you know for sure your ISP is doing it ?
There is online web based services you can use to test for throttling eh.
Break it down bit by bit by verifying everything.. 1 step at a time.