There are a ton of electronics today that use wall wart power supplies. These power supplies are really bad at holding their voltage output correct. The issue with this is that electronics start to do funny things when they get bad power into them. Over the years I’ve seen routers, switches, phones (the latest), and a whole host of other electronics develop strange behavior (packet loss, dialing failure, lockups, etc.) when the voltage creeps up (as they tend to do.)
Before you go replace your expensive piece of equipment grab a volt meter and verify that the output voltage matches what the power supply says it should be outputting. If it’s not within 10-20% of the output voltage get a universal power supply (like this one) with at least as much amperage as the original unit. Set the output voltage on the universal power supply at or slightly (10%) above the stated output of the original power supply. Find a tip that fits (most ship with a variety of tips). Make sure you get the polarity on the tip correct (match the original power supply.) The easiest way to tell polarity is to look at the old adapter. It will generally have a line figure that has + or – pointing to the center and the other sign pointing to the outside. Test and see if the power problems go away.
Don’t know how to use a volt meter? Simple. Get one cheap (like this one). Set it for DC Volts. Connect one lead to one side of the connector (generally inside) and the other lead to the other side. The display should show you how many volts are being output. Don’t worry about positive/negative — that’s just whether you have the leads reversed or not.