Wireless connection very slow with capsman

Hi..
I have a network of one routerboard and 4 basebox2 connected to it, I am using capsman for managing my wireless network.
My problem is that I have 4 network printers connected to the wireless and when I try to do scanning the scan is very slow and taking to long to scan and sometimes the printer stop and jamming and even users can not print. I checked evrything but I did not find a problem clients can use the network and internet without problem only thing I noticed that in logging I saw “wan link down” so please any help will be very appriciated.