W2008R2 trust with W2012R2: Synology diskstation asks for credentials

Hi,

I have a 2 way trust between a Windows 2008 R2 and a W 2012 R2 server which works fine.
I can access shares on both sites without a problem. Then I have this Synology diskstation which is added to one of both domains. I can access the shares of it in 1 domain, but in the other domain I'm asked for credentials.

Please advise.
J.

Jan Hoedt