USB Tethering - MT300v2 & MT1300

I have been using Android phones and tethering them to MT300v2’s and an MT1300 to get Internet connections on various small networks.

Speeds vary depending on network and location but they are normally pretty good speeds on 30Mbps to 80Mbps.

I recently set-up a new one and the Android phone (OS13) is getting download speeds of 150Mbs. If I USB tether this directly to a Windows laptop I get download speeds of 130Mbps but if I go via the MT300v2 or MT1300 I get just 3Mbps!

Any ideas?