Hello, we are traveling to Nuremberg and Rothenburg in November, and I was wondering if anyone could help me with a way to get from Rothenburg to Berg Eltz Castle. Can you get there by train and is a day trip feasible?
No, Burg Eltz is not a feasible day trip from Rothenburg. It is over 3 hours each way by car. By train it would take much longer and require transfers plus a bus.
November is a long way off. If your plans aren't set in stone, and if you're flying into FRA (Frankfurt) then you might re-plan your first day or two. But first you will need to find out whether Burg Eltz will even be open in during your visit. It normally closes in the first week of November. I don't see the calendar for 2022 yet.
To get there... When you leave the airport, you would take the train from the FRA airport train station via the Rhine River and Koblenz to the town of Moselkern on the Mosel River (where you will catch the trail to Burg Eltz.) See the trail at the bottom of this map.
It's probably best to do the hike the following morning. Moselkern has a few places to stay overnight. But many visitors overnight nearby in Cochem, where there's a ton of places to choose from. The map below shows Cochem, Moselkern and all the other Mosel River towns with train stops.
https://assets.static-bahn.de/dam/jcr:c3b41a1d-30c0-4d71-98b9-34f8fe093d50/190970-258769.pdf
The castle you see in that photo of Cochem is Reichsburg Castle in Cochem, which is right in town and has a winter schedule for tours in November.
Another area castle that you should consider is Marksburg, on the Rhine near Koblenz in the town of Braubach. It's open year-round, and it's terrific. The map below shows Marksburg's location as well as the location of the many other Rhine River Castles: