The speed you can get is up to the client and the noise (interference) in the area. However, try this and report back.
Interfaces / wlan1 / Wireless tab:
- Mode: ap bridge
Band: 2Ghz-B/G/N
Channel Width: 20/40Mhz eC
Freguency: 2437
WPS Mode: disabled
Frequency Mode: regulatory-domain
Interfaces / wlan1 / HT tab:
- check all Tx and Rx Chains