Scope:
All Barracuda Link Balancers
Answer:
The most likely explanation for losing access to the Web Based User Interface when plugging in the WAN ports is that there is no subnet mask configured on the LAN IP. To resolve the issue, configure the subnet mask by navigating to Basic > IP Configuration.
Link to this page:
https://campus.barracuda.com/solution/50160000000ILEZAA4