This is the Nancy train station as it looked in 2017.
There are no direct trains from Frankfurt to Nancy, so I usually take the TGV from Frankfurt to Strasbourg and change there for a regional train to Nancy. This takes three hours and 46 minutes, including 19 minutes in Strasbourg between trains.
As of 2022, this is the only daily connection with only one change of trains. Otherwise, you have to change two, three or even four times, which makes the entire journey much longer.
In other words, it takes just as long — or longer — to get from Frankfurt to Nancy as from Frankfurt to Paris, even though Paris is twice as far away.
When the new high-speed train line TGV-Est was being planned, it was clear that no more than one city in Lorraine could be connected. Both Nancy and Metz wanted this honor. They fought so bitterly over this issue that in the end neither of them got the station. The TGV line was routed halfway between the two cities and a station called Lorraine TGV was built out in the countryside, where it has turned out to be of little use to anyone.
Nonetheless, there are several direct TGV trains each day between Nancy and Paris. They just have to use the slower traditional tracks for a while, until they get to the new high-speed tracks. I took one of these trains in June 2018, leaving Nancy at 12:24 (or 12h24 as they write it in France) and arriving in Paris (Gare de l’Est) at 14:02. We had one brief stop along the way, I believe at Champagne-Ardenne TGV, near Reims.
My photos in this post are from 2007, 2012 and 2017. I revised the text in 2022.