How come can't use 300Mbps with N setup?

RouterOS General
1

We are using Version 5RC4 and can’t get max modulation only 270, we are using nv2, any ideas?

2

Cant speak for NV2, but my laptop is connected at 300mbps right now.

3

One of the MUM presentations stated that NV2 uses a long guard interval only which accounts for that rate.