The key word on the GL.iNet webpage is “Max”. Nearly all 2.4GHz wifi routers advertise Max 300 Mbps, but few or none reach that in real life situations. To me, 80-100 Mbps is good because I generally only get 20-30 Mbps over 2.4GHz wifi, depending on wireless band congestion, distance, obstructions, etc.
Are you able to switch over to 5GHz wifi, which should give much higher speed?
I do not work for and I am not directly associated with GL.iNet