Hi
If u are using IP address as server name in any of ur adsm client in dsm.sys
file.
Or any other applications as websphere .Pl reflect the changes accordingly.
Pl see that since u are changing mask and default gateway,then ur
server in on different network if I am right.
Pl see that what is average round trip time of ur packet from any of ur
present clients.
See netstat -D o/p i.e packets are getting dropped on network or netstat -i
any collisions/jaggering.
Because now u have to cross router to reach the other end u need to be sure
that their are
no bottle necks on network.

If u get error mail me I will let u know to tune ur network.