No, I don't have a currently working DAP, it failed a couple of months ago, but as I said, I didn't feel like dealing with it at the time as I was quite busy with work.
Yes, I've tried different ethernet cables, though how that would be the cause would baffle me.
The DAP is connected to my DIR-857 via wireless (I forget if that's bridge or AP mode right now, not at home to check).
I've tested the DAP every which way, it's failed for sure, since this is the 3rd time it's happened.
I'd rather not give out my personal info to be honest, even via PM, so I think I'll just get a product from another manufacturer after this one is replaced.