Drobo B1200i not connecting with Gigabit anymore, only 100 Mb/s Full Duplex


I am not sure why, but my Drobo will no longer connect to my network using Gigabit speed, but only Full Duplex 100 Mb/s. The Full Duplex 100 Mb/s is reported in the Drobo Dashboard, and confirmed on my Router’s Admin Page.

So far I have done the following to troubleshoot:
Changed out the ethernet cable (no luck)
Connected the drobo to a different router in the house (also a Gigabit Router) (no luck)

Does anyone have any suggestions of what else I can try? It seems the Drobo Dashboard doesn’t exactly allow you to choose the speed, so it must be automatically selected somehow, but I cannot for life of me understand why it is choosing the slower speed now.