2026-10-18
Most tunnel problems that look like packet loss are an MTU problem. If the outer header adds 60 bytes, an inner packet of 1500 bytes no longer fits and the path either fragments or drops silently.
I keep the tunnel interface at 1280 and let TCP sort out the rest. It costs a little throughput and saves a lot of debugging. Path MTU discovery is useful, but only when every hop cooperates.
2026-09-02
Policy routing is easy to add and hard to audit. A single extra table, one rule with a priority, and a comment explaining why it exists is usually enough. When the table grows past a screen, it is time to draw a diagram.
2026-08-11
A five-line script that fetches a known endpoint and checks the status code catches most outages. The important part is not the check itself, but the alerting threshold and the note in the log that says what was tried before the alert fired.