Dont upgrade the firmware if it is old as the ability to use the TTN Forwarder is then depricated and removed loosing that option - so go careful. (I need to go check at which version but recall it being called out on a Forum thread). Basically once up and running there is little need to change f/w, unless it is really old, though security updates would be one obvious issue - sadly Laird forces us to choose - flexibiity and convenient namin or keep up with updates 
I have Laird GW’s in the field deployed >2 years ago working fine with older firmware…
Update: Found it in this thread Laird Sentrius RG1xx Firmware Update