ipv4 path is 1480 because of ADSL PPPoA Elsewhere I read that it should be 20 less for tunnel overhead but I think that's for static tunnels. I tried setting it to 1460 and got an error that it has to be between 1280 and 1428. Overhead for an AYIYA tunnel appears to be 72 bytes. So I tried 1408 (twenty less) which works. 1409 doesn't. Am I doing this right? Is this in an FAQ somewhere already or did I miss it?