Accessing Router problems

I have a remote location with a USRobotics 8054.
I connect using remote desktop to a 2003 server. Then use VNC or http
to connect to computers and routers.

I upgraded the firmware on this router. It seemed to go ok ?

The computers that are connected to it I think are working I can ping
them. So I think the router is working.

The old static ip address was 192.168.1.201

When I try to connect using this ip it does not connect to the router.
When I try using the default ip, perhaps it went to the default eg
http://192.168.123.254 specified by the manufacturer it still does not
work.

Can I ping a mac address or something else to see if I get some
response. I dont really want to go to the location unless I have to.

Maybe I cant access a 123.245 address if the network is 192.168.1.1
network? I'm unsure of this.

Thanks.