Drobo B800i disconnects randomly after working for a long time

Hi there, my drobo b800i has worked for years, but suddenly started disconnecting. When disconnected, seemingly at random, the drobo will not show up in the Drobo Dashboard. The drobo can still be pinged from the client computer after a few seconds of unavailability. Rebooting the computer or the switch does not resolve. Using the power button on the drobo is all that fixes it. This happens almost daily, sometimes more than once a day. I changed computers, routers, and it worked for a week, and then began doing the same thing. I lastly took the router out of the equation and now have the drobo connected directly to the new computer, no improvement.
MTU size is 1500, so jumbo frames not the issue. Also has worked for a long time until recently. Also updated the Dashboard version to 3.5.0, no change. Reverted to 2.6.4 on new system to test last known good configuration, but no luck. Windows 10