Drobo 5D and Dashboard connection

I’m having trouble with dashboard detecting a Drobo 5D, and transfers (writes) to this unit are really slow.

I decided to try reviving a long-unused Drobo 5D on an old HP Pavilion now running Windows 10.
I thought the Drobo might be a good place for extra / archival backups.
To test this, I upgraded the dashboard & put in 2 WD drives (8TB & 6TB) as place holder disks.
It was very difficult to get format to work - dashboard kept losing contact.
Likewise for Drobo firmware upgrade.

I moved the unit back and forth between the 2 USB 3 ports on this old PC, & I also swapped USB cables. Same results. Dashboard loses & regains contact with the unit - usually fails as soon as
I tell it do something (change its own name, show storage available, &c).

I connected the unit to a good USB 3 hub. Same results.

Format must’ve worked eventually. The disk lights are green & dashboard stopped complaining about their state in the short periods it stays connected.

The Drobo unit’s volume does connect to the windows host. I’ve been copying a few backup files back and forth to see how this works. It looks like the speed bounces around, from about ~17 MB/s to under 1 MB/s. It stays around 1-2 MB/s.

I have a variety of Seagate & WD external drives on this host’s USB 3 ports and/or the hub, and they function well - consistently about 18 MB/s. Not great but an order of magnitude faster than the Drobo managed, on the same bus.

There seem to be similar problems reported elsewhere with no resolution. This doesn’t seem too encouraging. Any advice appreciated.