RG520N-EU - enable ADB

Hi folks,
I have a RG520N, firmware RG520NEUDBR01A04M8GA, and I am trying to enable ADB, but I cannot detect it from ADb tool
I understand should be the sixth bit in
+QCFG: “usbcfg”,0x2C7C,0x0801,1,1,1,1,1,0,0
is this correct ?
Do I need a key for unlocking ADB? Running AT+QADBKEY? returns an error.

Thanks in advance

AT+QCFG="usbcfg",0x2C7C,0x0801,1,1,1,1,1,1,0 ## Enable ADB
for unlocking ADB AT+QADBKEY?

Thanks, ADB now enabled.
Key was not needed on this device.

I can now telnet to the module after
mngcli set ARC_SYS_MPTEST=1
mngcli commit.

Second question:
I changed the APN with
AT+CGDCONT=1,“IP”,“ibox.tim.it”

AT+QMAP=“MPDN_rule”,0,1,0,0,1,

but still no connection.

Any suggestion or workaround ?
Thanks