Unable to see Shared Folder / Drop Box on wired LAN

I am unable to connect to another Mac on my wired LAN (Netgear wndr3700), and it is unable to connect to my machine. We cannot see each others’ Public Folder / Drop Box.
We can see each others Macs in the Shared section of the Finder’s sidebar, but trying to connect fails: “The server … may not exist or it is unavailable at this time…”
Both are running 10.6.4 Snow Leopard SL. No Windows machines on the LAN - so this should be AFP only.
We can see and connect to another Mac running 10.4.11 Tiger with no problem. BUT it is unable to connect to either 10.6.4 machine.
Firewall on both machines: On; File Sharing (AFP) set to “Allow incoming connections”; Stealth mode Enabled (toggling doesn’t change); “Automatically allow signed software to receive incoming connections” is Off; “Block all incoming connections” is Off. Some other apps and services are set to Block… (krb5kdc, numbed, smbd…) AppleFileServer is set to Allow.
Sharing: File Sharing Service only is On:
Hard Drive - Everyone - Read & Write
Users - Everyone - Read Only
~ (My Home Directory) - Everyone - Read Only
Public - Everyone - Read & Write
Drop Box - Everyone - Write only

Thanks for any suggestions.