Hi all !
I use Mikrotik RB1200. We have 150 PC users in office. Sometimes we have no internet connection for 1-2 minutes. I am doubtful of reaching the max user number. I couldn’t find max user number in specificiations (I don’t know if it has max user number or BW )
I am really sorry for my English. 
There is no such thing as ‘max users’ per router.
There is, however, something like maximum number of simultaneous sessions per router.
If you download a file, that counts as a session, opening a webpage is like 50 sessions (a download for every image, html page, stylesheet, etcetera..)
Every router has a maximum number of sessions it can handle.
Low-end routers can do like 2000 sessions simultaneously, high end routers can do many millions of sessions at a time.
If the session table is full it you cannot establish a new session and everything seems broken, except for sessions that are already in the session table (like a big download).
Our Metro Ethernet comes to Labris Fire Wall and then goes Mikrotik and from Mikrotik to switches. Sometimes we can’t acces internet but not for all users. 1-2 min later access is OK (i do nothing). I couldn’t solve this problem. What can be the reason/reasons. Do you have any idea? I need your help pls. 
Thanks for all !
monitor cpu usage and memory usage and interface status to seek where is the problem
check rb1200 logs
Also monitor the amount of sessions you are using.