DNA does not follow a surname, so common surnames can be a red herring if there are a couple (or more!) lines of descent that have a '?' not many generations back. You might share relationships on completely unexpected lines, or through step-siblings.
I've found some useful matches on Ancestry DNA, which have been a real comfort in confirming my paper-trails back 4 or 5 generations.
But you can only link up with the paper trail if;
1. It exists (not everybody leaves the right paperwork behind!)
2. You and your match have 100% accuracy on all your lines of descent
If the person you are seeking a match with has incorrect data on their tree, then I should put your energies somewhere else. Especially if they seem to be expecting you to come up with the answers. They sound suspiciously like the 'click and paste' genealogists who rely on Ancestry hints, or the first answer they come across. If you want to continue, that's the joy of research, but you'll be needing to check every line of descent for errors, not just the one you currently think is correct - since they might have got an incorrect link elsewhere, which, once corrected, might prove to be your missing link.
Are there any common matches between you and this match? Or do they come up as a common match between you and a different match? Focusing on one or two trees can help when you start to see them converge, although it multiplies the number of lines of descent to investigate. I found it useful to create my own lists of 'sub-groups- matches that seem to link up with each other, but not with other 'sub-groups'. Then when I start spotting common lines of descent amongst them, I can start to focus on whether that might be the line that connects to me (although that still might just be a coincidence and the common line/s with me be completely different).