Trying to cut over to a new router/core switch stack and have been running into issues with some of our customers. Their workflows are dependent on WAN circuits that are being deprecated in the cutover and they just don't want to adjust because they're afraid of the downtime. Not that it would even be that much downtime, since the NAT/Trunks/Gateways are already configured and the LAGs just need hardware and the routing table scripted in.

People just don't understand that occasionally we have to go dark for 30-60 minutes for critical upgrades that just can't be done with HA due to the outdated hardware we are trying to move off of.

Their unwillingness to play ball is what keeps us so out of date in the first place.