If you upgrade the BIOS of an rCell Modem to 5.x or higher, there will be no access to the Telnet Radio Access via the GUI. It is just hidden.
You can access it again:
To enable Telnet Radio Access on 5.x.x firmware builds
the link is
https://192.168.2.1/cellular/telnetRadioAccess (mind capitalization).
if Telnet Radio Access is already enabled on 4.1.0 and you flash upgrade from 4.1.0 to 5.0.0 and do not do a hard reset, Telnet Radio Access should still be enabled.
You can verify this by going to : https://192.168.2.1/cellular/telnetRadioAccess