I use a RB751U-2HnD as home hotspot (firmware version 5.22). The routerboard works fine until I use a bit torrent client on my Linux laptop. In this case the Mikrotik reboots every time after a couple of minutes. In the Mikrotik log I didn’t find anything of useful to understand the issue. The only messages I found are of this type:
jan/01/2002 02:00:02 system,error,critical router was rebooted without proper shutdown (cause 1)
*) fixed problem - netinstall for x86 did not work;
*) lcd - added take-screenshot command;
*) lcd - fixed calibration, fresh boards no longer require recalibration;
*) optimize memory usage - makes 32Mb routerboards more stable;
*) support BandRich modems with newer firmware;
*) ipsec - authentication using certificate store but without CRL checking for now;
*) added feature - flash can be partitioned on routerboards and
separate versions can be installed on each of them (requires latest firmware);
*) fixed problem - after restoring backup, it gets restored again on every reboot;
*) improved router performance when dhcp client/server present in system;
*) fixed vlan on bond after reboot;
*) fixed occasional queue kernel crash;
The problem hasn’t been completely resolved. I applied the suggestions and now the RB reboot happen once every 3 days.
I think I’ll never build an hotspot with 32MB RAM!!!