New here


Hi, after testing a 4G connection using a MG21, I am seeing packet sizes of 1280. 

Does the MG21 limit the MTU over a 4G connection?

Kind of a big deal

You may find this helpful - 


Robin St.Clair | Principal, Caithness Analytics | @uberseehandel
Here to help

Hi Guitartabman,


Is this issue still present for you? We're also experiencing the same with our MG21s, not on any other LTE modem.

Getting noticed


it would be interessting if this issue is still up to date and if somebody could give an update on this! We´re facing that problem as well but only with some ISPs...

Meraki confirmed that there is a bug in the software on the MG21 that results in an incorrect MTU size of 1280 when the mobile network doesn't provide the MTU size. They are working on a fix in a future software release. 

Getting noticed

@alex_n thanks for responding and the information! maybe you know what version(s) are affected from this bug and if it`s noted in the release nodes as bug?

The bug is present in the 1.9, 1.10 and 1.11 firmware (and afaik also in 3.x). We're waiting for a new (stable) firmware release in which this is resolved. The bug is not listed in the Known Issues.

thank you @alex_n !

I absolutely cannot understand why a known problem is not listed in the release notes... I probably could have saved myself all the troubleshooting, really annoying!
A workaround or something known to you what could make it work in the meantime?

I absolutely agree on that. It would be helpful to have an up-to-date overview of all the bugs that have been identified on a particular software version.

Our experience is that the "Known Issues" gives a (very) limited overview of the actual issues that are known, not just for the MG but in general.

Get notified when there are additional replies to this discussion.
Welcome to the Meraki Community!
To start contributing, simply sign in with your Cisco account. If you don't yet have a Cisco account, you can sign up.