Beagle-Lab-shepherd, plus possibly "other." Ears say not a lot of hound, but everything else says some hound. General shape says beagle/Lab type, but there's something in the tail set and body shape that suggests a touch of shepherd.
People so often want to come up with two purebred parents for mixed breed mystery dogs. That's rarely the case.
The black and tan coloring is so common in the dogdom -- there's no reason to suppose that any customarily black & tan purebred (like a Rottweiler or Doberman) was a parent. (I do breed rescue for a rare breed of medium-sized and quite fluffy dogs. One color pattern is black and tan. When those end up in pounds, they are often listed as "rottweiler mixes." Pound workers aren't even trying! There is NO resemblance to a rottweiler, except the dead-common color pattern.)
The commercial DNA breed test is BS. People have sent in samples from purebreds and got back these hodgepodge "results" of mixes of breeds that aren't at all related to their purebreds. (Like, say, sending in a poodle sample and getting back a report that says that it is a collie-mastiff-pug mix.)
Yours looks like a pleasant, happy, physically sound dog. What more can one ask?