I'm using FileMaker Pro 4 (old, yeah I know...). It worked fine with multiple user when we were using Windows XP. Now that my two clients are on Windows 7 and Windows 10, only one user can be in the file at a time. We get this error: FileMaker cannot host a file because of a network error. Files marked as Multi-User will not be available over the network. (10013). It still lets us open the file, but only one user at a time.
I've researched the error, it's mostly regarding FileMaker using port 5003 (which I'm not even sure if my older version 4 is using?). Thus far I've tried dropping the firewalls, turning off my anti-virus & spam/adware programs (thinking they were blocking port 5003) as well as setting up the client with a fixed IP address, but to no avail. Any help what-so-ever would be greatly appreciated.
Port 5003 is used when accessing a FM database from outside the local network, so if the clients are on the same local network then port 5003 would not be the issue.
FMP 4 is not supported on Windows 7 / Windows 10. If you upgrade OS then be prepared to upgrade FMP.
There are many issue using software that old.