I see the error "Roku player error: malformed data" when playing back certain recordings.

The recording is (obviously) included in the listing of recordings, and it will start playing for 10-15 seconds, but then playback freezes and this error is shown for a few seconds.

In the web interface (http://hdhomerun.local), the recorded files mimics the tree structure of recordings on the disk volume where recordings are placed. Each recorded file is a URL, e.g.:
http://hdhr-<device-id>.local/recorded/play?id=<guid>

I would like to be able to paste that into my media ...

Got another enclosure with backwards compatibility to USB 2.0, and it worked. Let FLEX initialize it, and then took it to my Ubuntu box to rsync the old volume to the new volume.

That is in progress as I type (a gig takes a while). I will edit this reply when it completes and I am hopefully able to ...

Yes the diagnostics confirm the original 1TB drive and a 2TB drive I connected to test. Apparently they are not showing my connecting the 8TB drive several times. A reminder I can connect it to an Ubuntu box and a Windows box and all is well on each.

I have reconnected as requested. Also tried ...

Drive is an 8TB HGST Ultrastar He8 SATA drive from here:
https://www.amazon.com/dp/B08W1PRTNJ

in an external USB enclosure that has its own power from a wall wart from Amazon here:
https://www.amazon.com/dp/B0D6RH6JBH

Drive is not detected and I have already enabled Send Diagnostic Information. As ...

Experimenting with the FLEX, it sees a bare 1TB or 2TB drive just fine and offers to format, but on a larger drive it is silent. Larger drive works just fine on a Linux or Windows system. I sure hope there's a software fix for this. If it's not going to let me set expirations or episode keep limits ...

I've verified I can see the current hard drive on my Ubuntu box, the directory organization is straightforward. So copying from old to new on that box would seem to be pretty simple.

you'd probably be able to get away with disconnecting the original drive, then hook up the new/larger drive to the ...

Thanks for the Linux suggestion, I have an Ubuntu box I use for MythTV so I can mount old and new (after initializing the new on Flex 4k) and copy across there, then put the larger drive back on the Flex 4k and hopefully all will be good.

Thanks, that's too bad, it would be nice to reuse old drives to add to storage. I don't want to use NAS storage for media and in any event with ATSC 3.0, storage requirements increase significantly regardless. If I have a pair of mirrored 1 TB drives on my legacy NAS, I'm still short.

So it seems ...

I have a Flex 4k with a 1 TB hard drive connected to the USB port. It works great.

I know I can replace the hard drive with a larger one to get more capacity. But I already have another 1 TB drive that I would like to connect to double capacity. I could simply use a USB hub to connect the hardware ...