More often, I think, you are going to say that you are concerned about the problem. You're worrying about it.
On the other hand, you may be involved in the problem, working on
solving it, perhaps. Then you'd be concerned with the
problem. This is not as usual, I think, in the case of problems.
More often, we use concerned with when explaining the association of some subject matter with another.
These computations are concerned with subatomic particles.
I'm not sure what a modem is, but it's something that's concerned with computers.
AARP is an organization that is concerned with retired people.
CJ