Wireless Joint

As the title says, is it possible to reboot the M1 modem without rebooting the whole device? Or some AT command to trigger the cellular signal to reconnect (sort of like an airplane mode toggle on android?)

Yes you can do it by DM command
29000 <---this is offline-A
29100 <---this is offline-D mode, this takes the modem offline
29200 <---this is reboot the modem but will trigger linux and os2 reboot
29300 <---this is FTM (factory test mode)
29400 <---this is online mode, (puts the modem back online)
29500 <---this is LPM (low power mode)
so to take the modem offline use offline-D
then to put it back online use online mode
you can also use AT commands such as
AT!DAOFFLINE
AT!DAONLINE
to use those you will have to first pass either the openmep or openlock challenge

Thanks. I was able to use the AT!DAOFFLINE command, however the AT!DAONLINE command just outputs "error". For the DM commands, what is the command syntax and do I just send them over the telnet 5510 console?

I gave you the "syntax"
You send DM commands thru the serial port.