I need to see all devices that have connected in the last 30 days

I have just been asked to figure out how many devices connect to a wireless network That is Using an RB2011 as the router. Is this information logged in the router? If I cant get past history, is there a way to set it up to get future history. I can manually sort through the connected devices pretty easily if I need to, so I just need a list of connections.

With default log settings information about wireless client connects and disconnects is available. Problem is that on most (if not all) devices default logging is in memory only. So you either have to set-up remote log server or logging to disk. Either way you can analyze logs later (logging to disk creates plain text files) using tool of personal choice.

Be aware any connection will be logged (each connection if the device connects/disconnects 10 times in 20 seconds).
You will need to screen for new MAC addresses occurring in Wifi log to see “who” connected.

It might be worth looking into hotspot manager if you want to know/control who connects and when with more granularity…

With Splunk for Mikrotik you can see all what is going on.
Count unique clients, see when users connects, disconnects etc.

See link in my signature.