/interface print where type=ether
/interface print where type=ether Flags: D - dynamic, X - disabled, R - running, S - slave # NAME TYPE ACTUAL-MTU L2MTU MAX-L2MTU MAC-ADDRESS 0 S ether1 ether 1500 1578 10220 6C:3B:6B:55:1E:44 1 ether2 ether 1500 1578 10220 6C:3B:6B:55:1E:44 2 S ether3 ether 1500 1578 10220 6C:3B:6B:1C:1E:6F 3 S ether4 ether 1500 1578 10220 6C:3B:6B:1C:1E:44 4 S ether5 ether 1500 1580 10222 6C:3B:6B:1C:1E:44 5 ether6 ether 1500 1580 10222 6C:3B:6B:1C:1E:99 6 ether7 ether 1500 1580 10222 6C:3B:6B:1C:1E:88 7 ether8 ether 1500 1580 10222 6C:3B:6B:1C:1E:88 8 RS sfp-sfpplus1_CSS_sfp-1 ether 1500 1580 10222 6C:3B:6B:1C:1E:88 9 sfp1 ether 1500 1580 10222 6C:3B:6B:1C:1E:88
Where MAX-L2MTU: 10220
Change all max MTU
/interface ethernet set [find ] l2mtu=10222