Finder, shared missing

[Thompsonrh]

I have just purchased a new iMac with High Sierra and transferred my main HD files and settings across from my 2009 MAC Pro (tower with El Capitan). Im new to High Sierra. I transferred through Ethernet after transferring from my Time Machine backup stalled. So I know the Ethernet connection to my network and my old MAC is good. The issue is that I now cant see the old MAC in Finder on the new iMAC. I dont even see Shared in the sidebar. It is checked in Preferences. But I have my old MAC running alongside, connected to the same network and Shared is visible and it sees several devices in the Finder sidebar. But it doesn't see my new iMAC. Ive rebooted a couple of times but no luck. The Ethernet connection to the netwotk is good, Im composing this Post through that network & internet connection. Any thoughts please.