It's not unsolvable, there are detailed proposals for how to solve it and after announcing loudly they would never work, the EU recently changed its mind and announced they'd already started preparations for it.
The only reason the Irish border is being described as "unsolvable" is because that suits the agenda of people who want the referendum to be ignored (as in Europe they always are).
The only reason the Irish border is being described as "unsolvable" is because that suits the agenda of people who want the referendum to be ignored (as in Europe they always are).