USB Modem Support in MX 19

[Steveruno]

Is the USB modem support code still in MX 19.1 or has it been removed?  I tried a ticket with Cisco/Meraki support and they finally came back and said they did not know and quoted the generic language about lack of support in MX 18 and later.

In my situation I have needed the USB modem twice in MX 18 to reboot the MX after the DHCP processes quit working causing  both WAN and LAN clients to fail as their leases expired.  My educated guess is that if the USB modem code is still in MX 19 then my USB modem would continue to work as it worked in MX 18.

[alemabrahao]

USB modems with MX/Z series devices running firmware MX 18 or newer will be limited to best effort support and will not be receiving any future firmware fixes or improvements. 

https://documentation.meraki.com/MX/Cellular/3G%2F%2F4G_Cellular_Failover_with_USB_Modems

[alemabrahao]

Security appliance firmware versions MX 19.1.8 changelog

Important notice

• As of MX 19.1, Cisco Meraki will no longer support USB-based Cellular Failover on the MX and Z platforms.

New MX 19.1.8 stable release candidate: more fixes than Bob the builder - The Meraki Community

[Steveruno]

I am looking for someone that knows the answer to question.  You are doing what the TAC did and citing notes that have the wishy-washy wording to them.

[alemabrahao]

Because this is the answer. 😉

It was not removed (yet), but it's limited.

[PhilipDAth]

We've changed over to using the MX67C for new purchases.

The USB modem support was starting to get a bit flaky.

[Steveruno]

My thought was that if the code is still there and the modem has been working then it will probably stay working until the code goes away - at least for my purpose of remote reboots.  Just trying to get a straight answer on that and nobody really seems to know one way or the other?

[PhilipDAth]

We have not found that to be the case.  Since that code is no longer tested, we have found MX versions that are broken with some of the USB modems we were using.  Other USB modems work fine.

It has reached the point where we can be confident that our USB modems will definately work during a failover.  Some definately still do work - but not all.

[Steveruno]

I realized I was overthinking this.  I have backup WAN through 5G and the only thing I use the USB modem for is remote reboot when the DHCP fails in the Meraki.  The two failures I have had "USB Failover" would not matter as the client are losing their IP addresses as well as the WAN so there is nothing to failover when this happens.  I am guessing maybe the USB modem gets the IP address rather than the Meraki so that is why is why it still works?  IN any event as long as Meraki allows the interface to be reachable from the dashboard then it will work for my purpose.

[ConnorL · Accepted solution]

Hey @Steveruno 👋🏻 

The ability to use a USB Cellular modem is still present in MX 19.X, it will be fully removed in MX 20.

Using USB Cellular modems in MX 19.X may work, however the last official supported release was MX 18.2.

If you're experiencing issues with USB modems on MX 19.X, I would advise rolling back to MX 18.2. Support for this feature will no longer be provided should you experience any issues.

I would advise looking into alternative solutions such as the MX-C or MG series. 

[Steveruno]

Thanks this is the answer I was looking for.  Assuming I have no DHCP system failures in MX 19 I can probably let the USB modem go when it is time to go to MX 20...assuming MX 20 even runs on an MX-68?

[PhilipDAth]

Would it be fair to say that 18.2 engineering support for 18.2 has ended?

Is 18.2 actually still a currently supported release?

[ConnorL]

The end of support date for MX 18.2 was August 20th 2025. It was the last supported release for USB Cellular modems. So I'd only advise rolling back to this build should you face USB modem issues after upgrading to MX 19 whilst you explore an alternative cellular solution.

[Steveruno]

I have elected to back out to MX 18.211.6 as I found MX 19.1 and 19.2 seemingly cannot sort out the small switch I use for the T-Mobile 5G on Internet2.  In MX 19 the loges fill with IP conflicts.  Initialy I saw that the switch was using the same MAC address for both of the IP addresses and fixed that.  The MX 19 code would actually report the fixed IP address with the old MAC address even though the traffic captures did not back that up.  

Update:  I moved the affected Apple TVs to Wi-Fi and the "DHCP Problem" went away.  Not happy I have more devices on Wi-Fi that could be on Ethernet though.

Now back in MX 18.211.6 I went today to get new packet captures and the packet capture feature does not work?!?  It did work when I was on M<X 19.1 and MX 19.2

Then to add injury to insult with the release of iOS 26 some of the Apple TVs in my network now fill the log with DHCP failures.  This seems to be specific to the Apple TVs that are stereo paired with HomePods.  Meraki Support is basically saying do feature requests for all this.  The ticket is 13503021 if a Meraki developer wants to take a look?

[Steveruno]

Eventually I got captures to work and was able to catch the EdgeRouter-X sending traffic from the VLAN2 VIF on VLAN1 so I now see that MX19 was better than MX18 in that regard.  I deleted the VLAN2 vif on the EdgeRouter-X and will move back to MX19. That leaves the Apple networking problem?

[Steveruno]

The Apple networking problem went away after upgrading the affected AppleTVs to tvOS 26.1 Public Beta so it appears Apple figured out they did something wrong - but only on the newest model of AppleTV.  An older model I tried on the beta still has the problem.

[Steveruno]

Meraki sent this email out earlier this week: 

Hello Meraki customer, With the introduction of firmware version MX18.2, Cisco Meraki engineering deprecated ongoing support for USB modems on MX and Z appliances. You are receiving this email because we have identified that you have one or more USB modems connected to MX device(s) within your network. Details: Currently, MX and Z appliances on all versions of MX18 only receive engineering support related to critical security vulnerabilities for your USB modems. With the release of MX19.1, third-party USB modems may continue to work with a Meraki MX or Z appliance; however, the Cisco Meraki engineering team will not provide any support. Third-party USB modem support will be removed entirely in firmware MX20.1. All support for USB modems will be deprecated next year, on June 30, 2026. Recommended customer action: We recommend you work with your account manager or reseller to find an alternative connectivity solution, such as the Meraki MG, before all USB modem support is deprecated on June 30, 2026. More details about this deprecation and recommended next steps can be found in our FAQ. Thank you for your attention to this matter. If you have any questions or concerns not covered in our FAQ, please contact Meraki Technical Support for assistance. Regards, Meraki Technical Support