ESXi host(s) management uplinks keep going up and down
When symptoms are observed such as ESXi host(s) state changing to "Not Responding" when viewed from the Hosts and Clusters view of vCenter, and that "Not Responding" state disappears after a non-specific time period, there can be many reasons that could cause such symptoms.
1. Please review KB Article Understanding the difference between Not Responding and Disconnected ESXi hosts in VMware vCenter Server
2. Please follow the steps in Troubleshooting an ESXi host in a "not responding"/"disconnected" state
If the cause cannot be determined by following the steps in these KBs, please open a Support Case for ESXi Networking using the instructions at Creating and managing Broadcom support cases