Hi Patrik,
It's great to hear that Volker is alive and well!
If you are able to get in touch with him, perhaps he can also sign over his ownership of the domain to you, and/or someone else as well.? As it is, no one except him can do anything with the original domain, except for paying the renewal fee, when it comes due.? At this point, it seems that Network Solutions is only "hosting" the domain name.? When the renewal comes up again, prior to 6/30/2022, another hosting company could be paid much less, to just register the name, and no one will have to pay a "re-instatement fee".? Without ownership of the domain, none of this is possible, as transfer to a new registrar cannot be accomplished without ownership.
ScottC