[CentOS] Centos 7 as gateway - UDP performance is busted/awful?

[Tom Horsley]

> If you look inside the ICMP packet in wireshark, it will tell you
> who sent it and what MTU they said was acceptable.

Well, I'm definitely drowning in network confusion here :-).

Everyone's MTU is the default 1500, I checked all systems in
the path.

The wireshark display says 1516 in the Length column for the
NFS packet that always shows up before the ICMP errors. If I
expand the "IP V4" line in the packet, it says "Total Length: 1500"
for that READDIRPLUS Reply which says 1516 for the capture
length. It also has the "Don't fragment" flag set.

It looks like the 16 byte extra is confusing it, but I have no
idea why that is different than the IPv4 length info.