I have been debugging some weirdness for a while. You might want to do some
captures on the latest cero and look at checksums.

An unreasonably high number of checksum issues seem to be happening, but
there doesn't appear to be a whole lot of pattern to it, as yet.

I will simplify. I pinged locally and 8.8.8.8 and surfed the web, and a
symptom is that some other routers can't ping sometimes nor access much of
the internet beyond the gateway. They can always reach the gateway.

in the interim, the topology on this capture are

172.30.102.17 - laptop via ethernet to
172.20.102.1 - cerowrt 3.7.4-4 via ethernet to
172.20.6.1 - ubnt 3.3.8-26 via mesh to
172.20.142.11 - ubnt 3.7.4-4 via ethernet to
* 192.168.100.1 - cerowrt 3.7.2 capture point (yes, updating that)
10.0.10.1 - comcast box (yes, double nat, fixing that)

I took a capture on the se00 interface

tcpdump -i se00 -w/tmp/yurt.cap host 172.20.102.17

and stuck that capture there:

http://snapon.lab.bufferbloat.net/~d/yurt/yurt.cap

and then looked at it with wireshark with this filter

ip.checksum_bad == 1

and scratched my head at the error rate (about 1%) and the pattern (lack
thereof)

I will simplify in the mroning

-- 
Dave Täht

Fixing bufferbloat with cerowrt:
http://www.teklibre.com/cerowrt/subscribe.html