Where to find a quality power supply for the router?

Yes.

The issue tends to be about noise coming OUT of the supply and polluting via the AC, rather than into the devices.

Any linear power supply of the right voltage and at least the rated current will work.

Also, keep your network devices outside (closer to your wall outlet) of your power conditioner unless you have multiple banks of filtering.

If you put it on the inside, you'll pollute your clean power.

Best,
E

Sbooster for linear. Daitron for SMPS (LLC type). 

I bought this one for my router. Huge improvement in SQ. Extremely well built. I liked it so much, I bought a 2nd one for my Empirical Audio Off-Ramp 5. If you’re willing to spend a little more, this one is even better. Be sure to use a good power cord. Yes, it makes a difference.

It takes more than just a good LPS to make a router sound great.  I would recommend the AQVOX switch.  The stock supply is great.

Steve N.
Empirical Audio