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Subject: Re: [Bug 220351] Path MTU discovery works only after resetting an
 internal interface MTU (mpd5, ng_nat, ipfw)
To: "Herbert J. Skuhra" <herbert@mailbox.org>
References: <bug-220351-2472@https.bugs.freebsd.org/bugzilla/>
 <bug-220351-2472-lCDWr8PCgb@https.bugs.freebsd.org/bugzilla/>
 <87r2xzaw30.wl-herbert@mailbox.org> <87bmp3x7eu.wl-herbert@mailbox.org>
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Cc: freebsd-net@FreeBSD.org
From: Eugene Grosbein <eugen@grosbein.net>
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Date: Wed, 5 Jul 2017 00:34:24 +0700
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02.07.2017 23:57, Herbert J. Skuhra wrote:

> mpd: [B1] IFACE: Connecting tcpmssfix
> 
> But when I disable IPv6 on my network everything is working... even
> without tcpmssfix enabled.
> 
> Instead of enabling ipv6cp in mpd5 I've also tested with an IPv6 tunnel
> from HE... same issue. :-(

I do not think this is mpd5-centric issue, rather IPv6-centric.