I cannot bring the Highsite down, as I will have downtime problems with clients. I never installed it, the previous technician did.
I would like to upgrade, but
a) I need to know the archtecture
b) I need to know if upgrading will be viable on this specific board.(I have upgraded on some older boards, and the OS just crashes and my CPU usage goes up ten fold)
Why do you want to upgrade? Are you missing features that 2.9.51 doesn’t offer? 2.9.51 is stable and still running fine on my older rb1xx and rb5xx routerboards. Some have uptimes of more than 1 year.
Your board is a rb1xx family routerboard. As Normis implied “/system routerboard print” will give you the model number.
The rb1xx boards are reliable but a bit sluggish compared to today’s RouterBoards.
It sounds like it occupies a critical location in your network. I would probably leave it at 2.9.51, or else replace it with a newer RB4xx RouterBoard rather than risk upgrading to a new major version.