when one user start download i get avery hight ping of dns and avery slow enternet prosing.
im using routeros v3.30 with hotspot only 2 lan cards . how can i solve this proplem pleas? 
Ping is low until you start to browse. In other words the car idles but when you put your foot down it chokes.
I’ve experienced pings going up on my network when I reach capacity or have poor links.
What is the power level of the link, ccq etc?
do you have a tx/rx limit set and are you ‘hitting’ it?