Did Apple Change Its Networking Protocol with Mt Lion?

[mrlynn]

Since installing Mountain Lion on my iMac, it cannot connect to my OS 9.1 G3 over the local network, and vice-versa. I get this message on the iMac:

There was a problem connecting to the server. . . wrote:
The version of the server you are trying to connect to is not supported. Please contact your system administrator to resolve the problem.

The two used to see each other, with the iMac running Snow Leopard.

/Mr Lynn