We have a weird issue where multiple switches are losing connectivity only on the management vlan at different times. It only happens for less than five minutes and then comes back up. It is happening on 4510's and 3850's. Nothing shows up in the logs. One thing that appears to fix the issue permanently so far is to change the vlan's IP address on the switch. It seems like every time we install a new switch though this happens to it and we would like to find the root cause. For example, we have tried replacing an entire 4510 and the issue persisted but changing the vlan IP did fix it.