I scheduled a major maintenance window involving a firewall replacement, exposing several services externally, migrating from ISC DHCP to Kea DHCP, and moving three networks to VLANs. I prepared documentation, mapped the environment, and planned the changes, but the implementation went badly. I got stuck on issues that seemed simple and spent nearly 24 hours troubleshooting. After getting some sleep, I planned to continue working on how to reach tagged VLANs through my untagged migration network or VPN. I'm feeling overwhelmed and foolish—how would you handle this situation, and what should I change about my process next time?
4 Answers
Take a break and get some sleep before continuing. Lack of sleep makes network troubleshooting dramatically harder, especially when you’re already stressed. Document what changed, preserve the current state, and work through one issue at a time. You’re gaining valuable experience from this, even if it feels awful right now.
This sounds like a change-management problem more than a competence problem. A firewall change, a DHCP migration, exposing services, and three network redesigns are multiple projects. Write a short review afterward: what worked, what failed, what assumptions were wrong, and what access or rollback tools were missing. That post-change review will make the next migration much smoother.
You’re not stupid—you tried to combine several substantial projects into one change window. The biggest lesson is to split them up: do the firewall separately, then DHCP, then the VLAN migrations. Each change should have its own tested rollback plan, and you should leave a large portion of the window free for unexpected problems. If the environment is unstable and you can still revert safely, rolling back is often the best choice.
The other danger is that when several things change at once, it becomes much harder to tell which change caused the failure. Smaller windows make troubleshooting and recovery far easier.
Also double your time estimates. A change that looks like a few hours on paper can easily consume the entire weekend once real topology and access problems appear.
For future work, stage and rehearse as much as possible before the maintenance window. Validate the VLAN tagging, native VLAN behavior, routing, DHCP leases, and management access in a lab or isolated test path. Keep an out-of-band or independent recovery path available, and test the rollback before making the first production change. A free day afterward for testing and recovery is much safer than scheduling back-to-back projects.
The DHCP migration may be possible with both services running briefly, depending on the design, so it doesn’t necessarily need to be part of the same outage as the firewall and VLAN work.
I’ve had supposedly simple installs turn into all-night investigations because of one VLAN or tagging mistake. Sometimes a few hours of rest are more useful than several more hours of staring at the problem.