Unable to access shares or ping server on different subnet after installing updates

We have a Windows 2003 server with Service Pack 1 on which we just
installed the following updates:

KB911567
KB908531
KB912812
KB890830
KB904942
KB911562

After installing the updates, we are no longer able to ping this
server from a different subnet or access any of the shares on it from a
different subnet. The server responds to a ping and computers on the
same subnet can access the shares located on it. All other functions
of the server work fine. This server also runs DNS and WINS (if that
matters). WIndows Firewall/Internet Connection Sharing service is
disabled.

What do we need to do to restore access to the other subnets?

I figured out a way around this and need to know if one of the updates
I mentioned tightened security in this regard:

Our servers are in one subnet and our desktops are in a different
subnet. These are port based subnets that exist on a network switch.
Before today, we did not have "Routing and Remote Access" installed on
the server in question. I have since added it and added a route to the
desktop subnet and all is now working.

The setup had been working fine without Routing and Remote Access for
months (as the routing is handled by the backplane of the switch) Why
the need to add RRAS now? Did something in one of the updates listed
change the way routing is handled?