hi,
pls be more specific so we can have a deeper look into it.
hmmmm
what´s the standard settings of your netcards / and on the new switch?
autoneogation ?
half duplex?
full duplex ?
10/100 or 20/200 ?
check your tcpip. what happens if you do a ping inside your network ?
is the https port open 431 for traffic ? what firewall ( if any) is running in at your network ?
greetings m.