Twice we had problem with WAN port of an MX84 after power shortage. (Yes I know the customer should have an working UPS). The ISP router and everything else came back after 15 minutes.
The ISP couldn’t see layer one on their interface facing the MX84. We had to send out someone who cheeked and restarted the MX84. Before resetting the MX84 we could see that it were no activity on MX84 WAN1 port.
Since the last time it occurred, we have changed the ethernet cable, changed the ISP router port facing the MX84 and upgraded MX84 software.
Both sides are set to auto negation. But It can’t have to do with negation, we even don’t have layer one.
Last time we got an explanation that there is no way to get logs when it´s a power shortage. If this is the case, it’s a crazy design of Meraki hardware.
Every system has a boot diagnostic and should have power enough to save last event even if its power outage.
Re: MX 84 WAN 1 fail layer one after power shortage
In the past we have had huge numbers of issues where certain DSL modems don't auto negotiate the Ethernet connectivity properly with MX devices.
Hence the reason I have a Netgear DM200 where rebooting the DM200 would result in the MX losing connectivity until either the Ethernet cable was pulled and reinserted or the MX was rebooted.
I'm unsure (in our case) if it's the MDI-X cable side or a strange speed/duplex combination
I would suggest if possible that locking the the uplink speed and duplex between the devices and then monitor them may be a reasonable starting point.
We had a similar issue in the early 2000s with late model PowerPC and early Intel Macs requiring locked ethernet settings at both ends and making sure you use a straight-through ethernet cable (to rule out MDI-X issues)