Start with the troubleshooting articles below. It sounds like maybe an issue with the Wi-Fi signal; the first article below will assist with further troubleshooting.
Thanks for using Apple Support Communities.
No still the same. Up until the Apple TV upgraded and I added a user/computer via homesharing all worked fine.
Including playing three quarters of the a movie that now wil not load at all (rented movie so have now lost access to it). I cannto play movies we have bought outright. Same deal - goes toload and spinning beach ball. up until the upgrade and for nearly 12 months we have not had any problems at all. Its not the WIFI it is something to do with the upgrade or homeshare and in doing a quick search I am not the only one with exactley the same problem but no solution to date.
Any further advise.
Add my Apple TVs (1 each ATV 2 and ATV 3) to this issue. So disheartening to no longer be able to watch my local library. It used to start playing within about 10 seconds. After update two hours later and still not playing. These are locally stored movies and tv shows, and I use Apple Extreme wifi router.