After installation, I ran the automatic network setup, and it created a profile 'Vodafone DE'. Since I had problems with data connectivity, I added another network profile Vodafone Internet which I use and which works fine.
GSM/EDGE and HDSPA connectivity are fine, no problems. Vodafone seemed to have some bugs with switching stations to LTE capability, and on these stations, UMTS data connectivity did not work, I had to disable UMTS and use GSM only. This problem of downward compatibility seems to be solved now.
However, when having UMTS enabled, in cases of cell switching under weak signal levels, the data connection gets lost. When I check the Network selection, I get "Vodafone Internet" registered for Internet access, and "Vodafone DE" for private network. Sometimes it is "Vodafone DE" for both. I have to switch manually the internet access back to "Vodafone Internet" and the private network to "My work network" to make UTMS data connectivity working again. In the GSM only mode, this does not occur.
I tried to delete the "Vodafone DE" profile since I do not need it, but this is not possible. Somehow it seems to be registered as default profile and is used as fall back if connectivity with the active profile fails.
Any idea how to solve this?