Limited speed on DynaDish 5 AP mode

Hello. Recently I’ve bought two DynaDish 5 routerboards, one of them used as AP and the other as client. While testing them in a distance of 3 metres (they will be used in a distance of 1km) , I realized that the AP doesn’t give me more than 20MB/s, when I used to have a Mikrotik SXT Lite5 as AP giving me a speed of 250MB/s (I have 600MB/s contrated).
The client antenna is working correctly, it can reach the 250 MB/s that the SXT Lite 5 is able to give. I configured the AP one as the AP SXT Lite 5 I have, so I don’t know what can be limiting my speed. I tried to factory reset, but there is no way. May it be a hardware limitation or my antenna is faulty? I bought the by Amazon, so I think it won’t be a problem. I also have updated them to the recently firmware.