What should Connection Settings in Windows Mobile Device Center/Active Stync be when connecting to a handheld device?

As of today, I am no longer connecting to my handheld device.

According to Windows Mobile Device Center, it can't even see it. Doubtless for this very reason, the device doesn't show up in Windows Explorer, either, anymore.

Some of the settings had been changed externally somehow - see this post for more details.

So I got to fooling around with it to see what would make it work again:

I warm-booted the devices several times.

I rebooted the PC a couple of times.

I changed the Connection settings (from "Bluetooth" to "COM1") and, although it seems illogical, toggled off "Allow USB connections"

I even changed out all the hardware: the cradle, the usb cable, and the power cable; I even put a battery in the cradle (it didn't have one before that). Nothing helps. Now Windows Mobile Device Center looks like this:

Is it my settings? What should they be to connect to a (Motorola/Symbol) handheld device?

Or are those (the settings) not even necessarily the problem?

UPDATE

Here it says:

"In the left pane of Sync Center, click Set up new sync partnerships. If your device doesn't appear in this list, then it doesn't support Sync Center."

It does appear, but this is how:

"View sync conflicts" shows nothing, nor does "View sync results"

When I try "Set up new sync partnerships" it doesn't seem to offer me what I need:

(I need to connect to a handheld device, not an old SQL Server DB nor an offline file)

UPDATE 2

It finally connected again.

Since nothing was working, I disregarded the advice and hints I had seen on the interwebs, and set the values to what seemed most logical:

I have all the following tickboxes checked, have "COM1" in the first dropdown, and "Work Network" in the second. When I accpeted those changes, WMDC (nee ActiveStync) shut down. I then manually restarted it, and joy of joys and wonder of wonders, it finally connected again.

UPDATE 3

Now the device lost its connection again "all of a sudden" - and the "Connection Settings" dialog of ActiveStync (Windows Mobile Device Center) somehow grew back its vestigial checkbox, "Allow data connections on device when connected to PC":

What the Deuce!?

For me, anyway, this is how the settings need to look:

Note that the "Allow data connections on device when connected to PC" tickbox is not even visible...?!?