German Embassy in Dublin

[irish resident]

Hi,
has anyone any advise regarding the following issue:

The German Embassy in Dublin has for the first time ever (in 10 years) requestesd that my husband submits his birth certificate for a visa application. They will not accept our mariage cert, which was issued in Germany, as a proof of his date of birth. Even the fact that he was resident in Germany himself for 3 years did not make a difference in their discision.
The birth cert is in his home country and just difficult to get a hold of.

I am German myself, my husband has a EUfam residence permit for Ireland.

What can we do? It means I am not able to travel to my home country with my husband.

Are there certain rights that I have as a German citizen?

Many thanks for any advise