RM551e-gl: Unable to Establish a 2nd PDN connection on VLAN

IoT Modules 5G Module
1

After looking through the RM551e-gl documentation, it appears the module should support establishing multiple data connections. I am trying to get this working.

I have a working connection using MPDN rule 0 on VLAN 0 using APN profile 1. I have successfully created another VLAN (VLAN 2) and am trying to create another MPDN rule for this VLAN. When I go to create the rule, I get this error.

[2025-02-05 14:56:52:353_S:] AT+QMAP="MPDN_rule",1,1,2,1,1,"FF:FF:FF:FF:FF:FF"
[2025-02-05 14:56:52:439_R:] AT+QMAP="MPDN_rule",1,1,2,1,1,"FF:FF:FF:FF:FF:FF"
[2025-02-05 14:56:52:439_R:] ERROR

Of note, I am trying to use the same APN profile as MPDN rule 0, which by default wouldn’t be allowed but, I have disabled the PDP duplicate check.

[2025-02-05 15:01:28:695_S:] AT+QCFG="pdp/duplicatechk"
[2025-02-05 15:01:28:780_R:] AT+QCFG="pdp/duplicatechk"
[2025-02-05 15:01:28:780_R:] +QCFG: "pdp/duplicatechk",1

I have also tried creating a second APN profile and using that instead only to receive the same error when attempting to create the second MPDN rule.

This is the output of the VLAN configs just so you can see I have a second one created:

[2025-02-05 15:12:48:410_S:] AT+QMAP="VLAN"
[2025-02-05 15:12:48:558_R:] AT+QMAP="VLAN"
[2025-02-05 15:12:48:558_R:] +QMAP: "VLAN",0
[2025-02-05 15:12:48:558_R:] +QMAP: "VLAN",2,1

Anyone have any thoughts?

2

Dear @iamgeek
You can try to use different APN to try again.

3

Ever figure this one out?

I was giving this a try on T-Mobile

So far here’s what I have established:

Enable the ability to set the same APN over multiple PDP contexts

AT+QCFG="pdp/duplicatechk",1

Create a new PDP context after the last one

AT+CGDCONT=7,"IPV4V6","fast.t-mobile.com"

Enable VLAN2 (causes reboot)

AT+QMAP="VLAN",2,"enable",1

Set your mpdn rules for VLAN0 and VLAN2

AT+QMAP="mpdn_rule",0,1,0,0,1

AT+QMAP="mpdn_rule",1,7,2,0,1

On the endpoint device establish a link to eth0.2 (assuming original NIC is eth0)

eth0.2 should get a 192.168.7.x assignment with a gateway of 192.168.7.1

Both 192.168.224.1 on eth0 and 192.168.7.1 on eth0.2 can reach the modem.

No luck on Internet traffic over eth0.2 so far though.

On the RM551E-GL module we see that different IP addresses are being assigned.

Screenshot_2025-11-11-16-32-09-96_61c78dc80ee02b53007c815fefe993e3
Screenshot_2025-11-11-16-32-09-96_61c78dc80ee02b53007c815fefe993e31164×547 79.4 KB

However, it seems only one new rmnet interface was created after establishing mpdn_rule,1 (rmnet_data2)
It’s IPv6 only. T-Mobile is an IPv6 only network though. Looks like QMAP logic is not making an additional CLAT/IPv4 rmnet interface.

Nonetheless didn’t look like IPv6 addresses on the Internet are responding over VLAN1 so there’s another issue there too probably.

QMAP logic seems unfinished.
I’ll have to compare behaviors to the RM520N-GL as well.
@silvia @Puck-Q @herbert.pan-Q @Jonathan.wang @Kasper_Cheng