Did you buy the MX second hand? ... View more

To add on what is already said: If PPPoE is used on the WAN, the MTU is automatically adjusted for the overhead If you need a different WAN MTU, Support can set this for you. But this reduced MTU is not accounted for when using non-Meraki IPsec VPNs and you will certainly run into problems. ... View more

I just had a different type of issue but similar. Our Provider refused to change from hard coding to Auto/auto  I was seeing 2 to 3 % packet drops every 20 to 30 mins.  They were seeing the errors on the client-facing side of the ENID. it wasn't till we made them replace the ENID and the new one was left on Auto / Auto did the issue resolve.  Seems the MX 100 did not like being hard coding with this provider. Or is using the Hard code something MX units don't handle well?     ... View more

Not sure of your problem but can confirm that Cisco UCS servers quite often (almost always) use VIC cards, which employ a form of virtualisation where you can split one card into multiple cards that are presented to the server/hypervisor - hence why you’ll only see the last couple of bytes on the MAC change.   As for your address conflicts, does the physical server have multiple network interfaces, and are you running VMs on the server? If so maybe the VM environment isn’t behaving properly… that’s all I can think of. ... View more