Pool members showing offline on production F5, but online on DR F5

We have two nodes set up on both Prod and DR F5. However nodes on Prod F5 are showing offline/unavailable, whereas on DR F5 they are online/available. We can telnet to both nodes from both DR and Prod F5. We performed another telnet test to the nodes from a windows server OK. Can someone provide any advice as to why these nodes are offline on Prod F5?

Thanks in advance