thanks for your question and welcome to Digi forum!
Please find below some useful links from 6310-DX user guide and Knowledge Base related to failover:
Further documentation for this model is available here: https://www.digi.com/support/productdetail?pid=5646&type=documentation
If you need any further help, please send us an email to firstname.lastname@example.org with SN/MAC of the router so we can open a case for your inquiry.
Digi support options are available here: https://www.digi.com/support
Digi Technical Support Team