What AppleTalk adapters can bridge LocalTalk to Ethernet? There are some adapter that allow LocalTalk printers to show up on ethernet, but I want to allow computers to talk. My IIgs has LocalTalk but all my Macs have only Ethernet. I have an old adapter, but the IIgs disappears from the Ethernet network after a few minutes.
What you need is a LocalTalk to Ethernet bridge.
It's possible to use a computer for this but in general the most reliable and easiest path is to use a device made for this purpose.
For example, I have a Shiva FastPath device that has a LocalTalk port and an Ethernet port. It will then transfer AppleTalk and IP traffic between them. If you only want AppleTalk to flow but not other protocols like TCP/IP that can be done as well, different products have different features and many products (like the FastPath) are configurable to selectively enable/disable things.
I'm using a Focus EtherLAN print box since many years for exactly that purpose with great success. It's small, reasonably fast, doesn't eat much power and it isn't restricted to only handle printers.
Sometimes, the box would simply hang but a power cycle fixes this always. After I put the box from a normal switch port on it's own spare AppleTalk-only interface on a Cisco Router, the problems were gone. Seems it can't handle too much broadcast traffic well.