Iranians, I Need Your Help

Alright, I have been thinking about and trying to find an answer to a really confusing question on the meaning of certain terms in both Middle Persian (Pahlavi) and Modern Persian, and their evolution (or corruption) throughout the ages. This question concerns the old name of the Iranian town from which my paternal family hails. It used to be called "Sodābgerd".

Now, it appears that the suffix "-gerd" in Modern Persian means "town" or "city", which indicates that "Sodābgerd" actually means "the city of rue" (rue is a type of herb). But I'm not certain of that meaning, since the suffix "-gerd" also appears in the name of "Yazdegerd" which is a Modern Persian corruption of "Yazdekert" in Middle Persian, and according to this link the name is composed from "yazad yazata" which means "divine being", and "karta" which means "made", so the name "Yazdekert" means "made from/by god". Here's the problem, if Modern Persian "Yazdegerd" is a corruption of Middle Persian "Yazdekert", then does that also mean that "Sodābgerd" is a corruption of "Sodābkert" as well? "Sodābkert" makes no sense, since it means "made by/from rue"!

Another confusing problem is posed by the original name of the Parthian capital of Nisa - "Mithradātkert" - which means "the fortress of Mithradates" according Encyclopaedia Iranica. This adds another meaning to the "kert" explained above. So we now have three possible meanings of the old name of my home town:

1) "The city of rue" - Sodābgerd

2) "The city made from/by rue" - Sodābkert

3) "The fortress of rue" - Sodābkert

Middle Persian "kert" apparently has two meaning here: "made" and "fortress". So "Mithradākert" either means "the fortress of Mithradates" or "made by Mithradates", which indicates that 'Yazdekert" could also mean "the fortress of divine being"! 

Which of the aforementioned three meanings of "Sodābgerd" is true? I'm really confused here, and it seems like the whole "-kert/-gerd" issue is a result of flawed scholarly reading of Middle Persian script rather than a case of one word having two meanings and a modern corrupt form.

Looks like the erroneous translation of "Yazdegerd" in Encyclopaedia Iranica was the source of my confusion.

It's really great that the old name of my "mother" town was graced by that of the legendary Sudabeh.