Hi, i found the RB 750 & 750G are preloaded with ROS v3.31, is that safe to upgrade?
Yes, it is preconfigured with some- ip dhcp and switches. Maybe the reason.
Is it safe to upgrade to v4? (as i see many complains regarding RB750 upgrades to v4)
What happen if upgrade failed and wanting to return to 3.31? Can’t find 3.31 anywhere 
just wondering..
cheers,
You should upgrade to v4.5
done!
Upgraded to ROS v4.5
Works like charm!!
I read that there is an OSPF issue with Version 4.x so that OSPF stop to work.
see here: http://forum.mikrotik.com/t/ospf-works-than-stops-by-itself/34964/1
I have some RB750G with v4.11 can I downgrade to 3.30? Will it work?
Or need the RB750G the Version 3.31? Can you send me the Version 3.31?
there is no OSPF problem in v4