There could be one of two things going on here. First, what version of
ComOS are you using. It wasn't until later ComOS versions that the
RFC for passing default gateway on PPP negotiation was implemented.
You should be using ComOS 3.5 if at all possible.
Second, Microsoft has a known problem with its ICMP and tracert.exe
programs in that with a Livingston term server (and a few others) it will
ALWAYS timeout on the first hop. In fact early versions of WS-Watch had a
selectable option for your pings, Normal ICMP or Microsoft ICMP. Unix
machines do NOT have this timeout problem even when connected via
Livingston Term Servers/Routhers. Even though it is Microsoft that did
not implement properly, it looks like it is going to be Livingston that
will come up with a workaround. They say that there is an RFE on it.
I suspect it is the second problem rather than the first that is your
problem. If the default gateway was not picked up at all, you would
have NO traffic getting out at all, instead of just timing out on the
first hop. With MS versions of traceroute, it is not unusual
to miss anything from the first to the third hop outbound. But routing
is not affected. If you are truely not getting a default route as shown
in a "route -print" or "netstat -r", then upgrade your ComOS.