Think I have found the major factor that causes the Linksys WRT54G V5 to
fall over in testing scenarios:  DNS.  For some historical reason, we're
trying to use libcurl without any DNS caching.  My implementation echoed
that and implemented it correctly and I was seeing a DNS request per request
on the wire.  The existing implementation tries to do that and has bugs
because it is clearing caching DNS data querying only once every few
seconds.  Once I started emulating the bug, comms through the WRT became
much, much more reliable.