Well, I guess the first question is as to whether you are referring to router firmware of the modem firmware. The “check and update” feature via the GUI for router firmware works excellently and this can also be accomplished by IC2 if you use it. But this does not update the modem FW.
To check the modem FW one must go to the “semi-hidden” support menu and look for the section entitled “Cellular module firmware update.”
To get to this page from the GUI, replace “index.cgi” in the and all that follows in the URL with “support.cgi.” (This is discussed in several threads here on the Forum. One can also use IC2 to accomplish this.
Peplink does not blindly make new modem FW available as soon as it is published by the module manufacturers so it it is possible there may be newer FW available “in the wild” which is not available to Peplink users. I’d suggest allowing the Peplink equipment to determine when new cellular module FW is available and if it is suitable for installation.