Hi @bigJ    IPv6 is disabled on the LAN side of the MX by default. Has it been mistakenly enabled? https://documentation.meraki.com/SASE_and_SD-WAN/MX/Design_and_Configure/Configuration_Guides/Networks_and_Routing/IPv6_Support_on_MX_Security_SDWAN_Platforms_LAN ... View more

@AaronMcElhinney that fix my error as well. I moved the copper uplink from SW1 to SW 4 and the issue was resolved. Same in my case both ports are identical. Thank you for sharing. ... View more