I purchased a 1 Gbps down/up connection and noticed that I was consistently getting 95 Mbit/s down/up, regardless of hardware configuration (router, no router, switch, no switch, connecting directly to the ONT, cat 6/6a cables, etc) and regardless of software configuration (VPN on/off, firewall on/off, OS Linux/Android, driver updates, etc).
When nothing seemed to help on my end, I finally called my ISP. They could confirm that my ONT is a decade old and that they can see that each port only allows for 100 Mbit/s down/up.
I went through so many stupid steps before finally testing a direct connection to the ONT which finally made me call the ISP. I guess that is the difference between being an educated network engineer and a self taught enthusiast… 💔
The ISP is going to replace the ONT for free.
Be aware that there are 2 standards for ethernet. See the tables for T568A and T568B termination. https://en.wikipedia.org/wiki/ANSI/TIA-568#T568A_and_T568B_termination I am not an expert, but my understanding is that most all hardware works with either standard. You just want to make sure both ends of the cable are wired the same way, otherwise you’ve made a crossover cable, instead of a straight-through cable. I do T568B.
Specifically B is the standard. Edit: the Wikipedia article has a more complete explanation as to why, but you should always wire to B unless you have an explicit reason to do otherwise.