я хоть и не житель германии, но вот что нашёл во Франкфурте. Может есть что близко из этого....
Where To Find Free Wi-Fi in Frankfurt
Here are a few other places where you can go:
* Coffee Fellows - on Kaiserstrasse 14, near the Mercedes Building.
* World Coffee - Grueneburg Weg 9, and Kaiserstrasse 10
* O'Reillys Pub - directly across from the Hauptbahnhof
* Starbucks - get 1 free hour with a purchase in participating locations
* Cafe in the Kunst Verein (in the Steinerne Haus next to the Römerberg)
* Euro Cafe - on the Kaiser Str. by the European Central Bank
* Bar Celona - The square behind the Katharina Church
* Yours Australian Bar - in the Schiller Passage near the Stock Exchange
* Burger King - Multiple locations
Ask for the password when you buy your drink or snacks.
Another option is to buy a monthly pass from the T-Mobile website. This will let you have access to dozens and dozens of hotspots in town (restaurants, cafes, pub, hotels, etc.) and make life just a little bit easier during your travels through Germany. If you have an i-phone, it will allow you access to wifi, but not data roaming
А это вот совсем свежее
The 15 Best Places with Free Wifi in Frankfurt Am Main
https://foursquare.com/top-places/frankfurt/best-places-free-wifi