It's only been an hour.
DLNA error 2104 usually is something goofy with the router, or a network interface card causing a timeout....at least in my experience.
1) turn off PS3
2) shutdown PC that runs PMS
3) unplug your router
4) let it sit for 10 seconds
5) plug it back in and let it boot up fully
6) turn on your PC and let it boot up
7) if PMS is run as service give it a few seconds once the login screen comes up, then turn on the PS3. If run as a task, login and start PMS then turn on the PS3.