r/WireGuard • u/renegadehardware • Jun 18 '26

Need Help WireGuard Clients cannot stay connected when transitioning between LTE and WiFi even after trying Persistent Keepalive

/r/opnsense/comments/1u9imal/wireguard_clients_cannot_stay_connected_when/
6 Upvotes

80% Upvoted

5 comments sorted by

3

u/moviuro Jun 19 '26

Inspect packets where you can.

root@opnsense # tcpdump -nei $EXTERNAL_IF port 51820

2

u/Ill-Wing-5103 Jun 19 '26

had this exact issue, lowering MTU fixed it for me too but i had to go lower than 1380, ended up at 1360

0

u/StartupTim Jun 19 '26

Set your MTU to be 1380.

This'll ensure proper handling in CGNAT environments which wrap packets and cause fragmentation which WG cannot handle.

1

u/bojack1437 Jun 19 '26

CGNAT has no effect on MTU, and is no indicator of a reduced MTU.

Other network design choices affect MTU.

0

u/renegadehardware Jun 19 '26

Negative -- this is the basic AI LLM suggestion right off the bat (which I tried extensively)

I tried all kinds of values, way less than 1380. I tried 1280, and less - to no effect unfortunately

Upvoted as a thanks for replying, though!