Bug #11291
closed
WireGuard MTU Can Flap between 1420 and 1500
Added by Christian McDonald over 3 years ago.
Updated over 3 years ago.
Description
The default WireGuard MTU is typically 1420. However , I’ve observed cases where the wg interfaces will flap between 1500 and 1420. Explicitly configuring an MTU on the interface configuration fixes it
I've nailed down clear reproduction steps...assuming that you have a WG tunnel and it's corresponding wg interface assigned.
- Go to the WG interface configuration and click save and apply.
- Check Status > Interfaces and the WG interface will have an MTU of 1500
- Go to the VPN > Wireguard > Tunnel configuration and click save
- Check Status > Interfaces again and the WG interface will now have an MTU of 1420
This is obviously problematic and was discovered by OSPF adjacency issues because the remote end had a fixed MTU of 1420, which is the WG default. I've disable MTU mismatch detection on both ends for the time being.
- Status changed from New to In Progress
- Assignee set to Jim Pingle
- Status changed from In Progress to Feedback
- % Done changed from 0 to 100
Looks good, thanks for the quick update
- Status changed from Feedback to Resolved
MTU is stable on current snapshots. It's 1420 even after save/apply on an assigned interface.
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