Can you dumb this down for me? I'd prefer to not have to buy a new router.
If you mean dumb down the concept, each device is identified by an IP, which is just a set of numbers. If two devices are assigned the same IP number on your wireless network, it can create issues.
By assigning a static IP or DHCP reservation, you are insuring that the device(s) gets the same IP number(s) each time it connects to the router, and therefore prevents any potential conflicts.
However, I somehow doubt it's an IP conflict, unless the conflict doesn't involve your PC. If it involved your PC, a notification would pop up telling you that there is an IP conflict, so you would know it. If the conflict is between your phone and a tablet, however, I don't know that either of those devices are set up to give you any notifications about IP conflicts, so it's possible that there is still an IP conflict issue.
If you mean dumb down how to actually create static IPs or DHCP reservations, well...that depends on what router you have, as each has a different method or menu location for changing that.