we have a strange problem with one of our OES Linux ( SP2 ).

It functions as a router and routes all our internal traffic to the
Internet. After startup, this works fine for about 5 minutes, but then name
resolution stops functioning.

We can still ping our gateway at the ISP and our name servers, but names are
not resolved anymore, and other IP addresses "further away" can also not be
pinged again. It is not the ISP, because when we connect another router,
this works fine.

Also, after a restart, it works fine again for a while but then name
resolution stops again to function.

This only started yesterday. Before that, the OES was working fine. No
configuration changes have been made.

Thanks and regards