https://github.com/javaee/jaxb-v2 is JAXB’s new home (jaxb.java.net now redirects there).

Issue tracker is at https://github.com/javaee/jaxb-v2/issues (though it seems some existing issues didn’t get migrated over, for example https://github.com/gf-metro/jaxb/issues/22)

I’m not sure where you are supposed to get official binary releases from; Maven I guess?

http://search.maven.org/#search%7Cgav%7C1%7Cg%3A%22com.sun.xml.bind%22%20AND%20a%3A%22jaxb-ri%22

http://search.maven.org/#search%7Cgav%7C1%7Cg%3A%22javax.xml.bind%22%20AND%20a%3A%22jaxb-api%22

Discussion group is apparently at https://javaee.groups.io/g/metro, but first you need to join the parent group https://javaee.groups.io/g/javaee

https://javaee.github.io/ has details of other the projects migrated from Java.net to GitHub