If you are using cAP as in RBcAP2nD, you can NEVER go over 100Mb when using it wired towards RB2011. There is only an Ethernet connection of 100Mb. You can physically not go beyond that (70-80Mbs max, I'd say). That 300Mb must be between Wifi devices connected directly to that AP and in ideal lab circumstances.
Other things to check (MUM presentation as guideline:
https://mum.mikrotik.com/presentations/ ... 286214.pdf)
- use local forwarding for CAPSMAN. Otherwise traffic first needs to be encrypted on cAP, send over the connection to capsman/RB2011 and decrypted again, all without HW offload. That takes time and thus bandwidth away
- disable B if possible. G/N or N only.
- adjust basic rates. 6 or 9 Mbps to start, maybe even 12Mbps or 24Mbps if your client devices accept it.
- check the used channels where the devices are located. Typically 1/6/11 are the best to use to avoid overlap but maybe others are already in that range ?
Lastly,
when you only have RB2011 and cAP, it might be worthwhile NOT to use CAPSMAN and setup the devices separately (which gives you more flexibility to set the best channels to use for each AP).