Help with old freeswan and old linux on old hardware.

I just stepped into a network support position to find a Pentium 100
running some long lost version of Red Hat Linux with FreeS/WAN 1.91
running as the VPN endpoint for our connection to our colocation
servers. To say the least I dont want to touch this beast with too
heavy a hand for fear of it breaking before I can document everything
that its doing. However, out of the blue a problem has apeared. While
the rest of the network can see the colo site using this box as a
gateway the box itself cannot conect out. This is a problem as it is
also our DNS cache for the DNS server at the colo site. Any ideas as
to what I should look for while trying to fix this?