IPv6 MSS range
SwimGeek opened this issue · 3 comments
Package version
1.0.20210606-2
Firmware version
v2.0.9-hotfix.2
Device
EdgeRouter X (SFP) - e50
Issue description
Wireguard allows you to set the MTU to 1280. For IPv6 traffic, I think that would bring the MSS value to 1280-60 = 1220, but that seems to be outside the range allowed by the configuration system.
command: set firewall options mss-clamp6 mss 1220
response: MSS must be between 1280 and 1492
I suspect it should allow mss-clamp6 value to be as low as 1220.
Configuration and log output
No response
I'm not sure if the WireGuard package is directly related to this issue, as it looks like an EdgeOS issue.
So I guess this issue should be reported to the Ubiquiti forum.
IME you are unlikely to need MSS clamping for IPv6. IPv6 normally does path MTU discovery correctly and therefore will work better without MSS clamping. Remove the mss-clamp6 section from your configuration.
delete firewall options mss-clamp6
IPv4 should also work better without MSS clamping, it's just that sometimes people find it just mysteriously doesn't when connecting to some remote servers.
Closing as not planned since there is nothing we can do to change the limits for mss-clamp6.
vchrizz correctly pointed out the Ubiquiti forums as the correct place to discuss this issue.