Need Help Reducing Noise and Blotches in Interior Render!

Hey everyone. I’m working on an interior scene, and I’m testing out different sampling settings to remove noise and those blotches on the back walls of my render but some difficulty finding the right settings.

I’m using 2.79b and Cycles

You can see that the back wall at the end of the hallway, the ceiling, and the wall just behind the chair have this blotchiness to them.

here’s a photo of the settings I used for this render

Radius was at 6 and Strength was .4 and I was using the standard Denoising, not D-Noise: AI Denoiser

I’ve included the blend file if anyone wants to take a look at it. Thank you for your assistance should you choose to take your time to do so!