MG21 MTU

[Guitartabman]

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?

[Uberseehandel]

You may find this helpful - 

https://usatcorp.com/faqs/main-mtumss-design-considerations/ 

[alex_n]

Hi Guitartabman,

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

[whistleblower]

Hi,

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...

[alex_n]

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. 

[whistleblower]

@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?

[alex_n]

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.

[whistleblower]

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?

[alex_n]

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.