I hate to offer advice based on one single datapoint, but I have an Xsurf, and it just decided to stop working after only having used it for a couple of years. That didn't make me happy.
Two Commodore A2065s I've had since the 1990s have always worked perfectly.
A common problem with older ethernet cards is the little voltage conversion box. If you can get at it with a multimeter while it's running, you should be able to find out whether that's the issue. The outputs are usually labelled or can be found easily by Googling. If it is that, you can probably find a cheap older ethernet card on eBay with the same kind of voltage convertor and swap them.
Other things to try are using a different switch or hub, or finding a hub with a 10base2 connector and using 10base2.
