Damp concrete floor in porch

[Truckeral]

I have recently noticed a musty smell in the porch, built in 1997. I have checked the concrete floor with a damp meter and damp is present just inside the front door. The porch was built on a brick foundation and a concrete screed infill. The DPM under the screed does not appear to extend up the side of the bricks at the front door, so moisture is tracking across to the screed.
If I apply an epoxy coating to the floor would that seal the concrete floor and stop the damp ingress?
Any advice would be appreciated.
Alan