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Cisco Meraki Documentation

Traffic Forwarding Issues on Firmware MX18.211


Cisco Meraki discovered an issue where MX75/85/95/105/250/450 networks running firmware version MX 18.211 with one or more traffic shaping rules configured as "High" or “Low” priority may incorrectly drop traffic being routed between VLANs or AutoVPN.

    Who is affected? 

    MX networks with:
    • MX75, MX85, MX95, MX105, MX250 or MX450 running firmware MX 18.211

    • One or more traffic shaping rules configured with the priority set to “High" or "Low”

      • Example of a shaping rule that will trigger the issue:Screenshot 2024-05-20 at 12.46.41 PM.png

    What is the impact? 

    MX incorrectly drops traffic being intended to be forwarded between VLANs or AutoVPN.

    Affected Models  

    MX75, MX85, MX95, MX105, MX250 and MX450.

    Affected Versions

    Versions prior to MX18.211 are not impacted.


    Two options available as a workaround:

    1. Change any shaping rule set to “high” or “low” to “normal”. (Traffic shaping rules configured via group policy are also in scope), OR

    2. Upgrade the MX firmware to, which contains a fix for the issue. Downgrading the MX to a another firmware version that had been previously used is also an option.

    What about customers who have already been upgraded?

    Cisco Meraki advises you to apply the workaround of either changing your traffic shaping rules as described above or rolling back to the previous firmware version. If you are still experiencing issues after applying the workaround or upgrading the MX to 18.211.01, please contact Cisco Meraki Technical Support for assistance.  

    What actions has Meraki taken? 

    Cisco Meraki has proactively cancelled all scheduled upgrades for MX Firmware Version 18.211. With MX 18.211.01 now released, where this issue is not present, upgrades may now be resumed. 

    An entry has been added to the known issues section of 18.211 firmware release notes under Organization > Firmware Upgrades. has been made available with a fix for the issue.

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