Thanks. I plugged in a USB to 2.5GbE adapter to a Mac Mini M2 and under Mac OS, I used Link Aggregation to combine them together into one virtual link. Then, I connected it to a PC. Tried to plug in a CAT6 cable to the built-in 1GbE port of the Mini but no increase in speed. Then, unplugged the cable and connected it to RJ45 port of the 2.5GbE adapter but there was also no increase in speed. If I recall correct, somebody said that I need to use two cables (one connected to the built-in 1GbE port of the Mini and another connected to the 2.5GbE port of the adapter) and then plug the other end of both cables to a switch or router (don't remember which) for Link Aggregation to work. The router is in another room so if the switch can get the job done without connecting it to the router, I just get a switch and put it in the computer room.