"Provider: Connecting" could mean an incorrect APN (but you have entered the correct one already), more importantly the missing values for the parameters listed below could mean that the modem is unable to read the sim card properly.
To eliminate the sim card being the issue right off the bat, I would try the Tmo sim card in a phone just to see if it can read it. If it fails, then simply replace it.
I would also try to insert a different sim card, restart the router, and look at the info again (even if it's from another carrier), at the very least SIM IMSI, SIM ICCID, SIM Phone Number should all be populated with some values regardless if you can connect to the internet or not.
The possibilities for the failure may be: defective SIM card, defective SIM card reader, or reading the incorrect slot. Some M.2 to mPCIe modem adapters may prevent the router's sim slot from reading the sim properly, depending if it's a top or bottom type sim tray adapter, so you could try moving the sim card from the router's slot into the M.2 to mPCIe adapter's sim slot. Also, make sure that the modem and the adapter are all connected to the main board nice and snug with the mounting screws.
If none of these suggestions work, then there's a possibility that the Telit LM960 is either defective, has a locked firmware, or some other unknown issue. It would be helpful if you could copy&paste the various command/status responses.
To read the network status (similar to Sierra's AT!GSTATUS?), but it's more cryptic with values separated by commas. The most important values you wanna look for are <PLMN>, <RSSI> and <IMSI>
AT#RFSTS
#RFSTS: <PLMN>,<EARFCN>,<RSRP>,<RSSI>,<RSRQ>,<TAC>,<RAC>,[<TXPWR>],<DRX>,<MM>,<RRC>,<CID>,<IMSI>,[<NetNameAsc>],<SD>,<ABND>
To read the SIM slot status.
AT#QSS?
<mode>,<status>,<active_slot>
The third value shows 0 for slot 1, or 1 for slot 2
To set the SIM tray detection method by trying all three <mode> values.
AT#SIMDET=<mode>
SIM detection <mode> values
0 - switch to SIM slot1 (factory default)
1 - switch to SIM slot2
2 - automatic SIM slot2 detection through SIMIN Pin
As a last resort, you could perform a full factory reset on the modem, then try the sim in both slots again.
AT&F1
AT+QPRTPARA=3
Then restart the router and try the sim slots again.
Missing values:
SIM IMSI :
Unknown
SIM ICCID :
Unknown
SIM Phone Number :
SIM Name :
Signal Information
Network :
-
CSQ :
-
Signal Strength :
-
