@sjn1965 

Did you have other devices connected to the same switch? maybe it took away some speed.

Or you could test the other way around:

router--a shorter cable to TL-SG105---20m cat7 to your computer to see whether it made any difference to the speed.

Ensure that the Cat 7 cable you are using is of good quality and properly terminated. Poorly made or damaged cables can result in signal degradation. Confirm that you are using the correct ports on the switch. Some switches may have one or more ports designed for higher speeds (e.g., Gigabit Ethernet), and using a different port could limit your speed. Check if both your PC and the switch are set to auto-negotiation for speed and duplex. This allows devices to automatically determine the best settings for communication. If one side is manually set to a specific speed, it might cause a mismatch.