[Bug 220351] Path MTU discovery works only after resetting an internal interface MTU (mpd5, ng_nat, ipfw)

[Eugene Grosbein]

02.07.2017 21:03, Herbert J. Skuhra wrote:

> Skype for Business (S4B) on Mac OS X 10.12.6 (Beta5) is actually
> trying to connect over IPv4. The connection fails until I lower MTU to
> 1440. After resetting MTU to 1500 and restarting S4B it connects fine
> for a while ('route -n get' default shows 1500). I use 'set iface
> enable tcpmssfix' in mpd5.conf and I've tried:
> 
> - set iface mtu and set link mtu/mru/mrru in mpd5.conf
> - set scrub ... max-mss in pf.conf

Please show output of ifconfig command for external ng interface.