Why is my Netgear JGS516PE only getting 100mbps with a 350mbps cable connection?

Also, as a side note, if you're connecting the router to the switch, confirm that the cable from the router to the switch is gigabit capable. Sometimes, older cables can cause these speed issues. You might want to replace it just to rule it out.

First, check what router you're using. Your Fire Sticks likely don't have gigabit ports, which could limit speed. Make sure your PC has a gigabit port as well. If both have gigabit capabilities, then it could be an issue with the cable itself. You mentioned you made the cables, so double-check the pinout to ensure everything is correct.