Repeater - Extender

Not necissarily a Comcast or Xfinity question, but I have always gotten some good advice and help here...

I have very minimal networking knowledge, but would like to add a couple repeater/extenders to my wifi.

I have a Net Gear AC1750 router.

I bought a couple cheaper extenders a year or so ago bt don't think I ever got them set up properly.

I tried again last weekend, but still didn't seem correct.

A LOT of what I saw for online help was old and referenced Windows 7.

Saw some things saying best to use same brand stuff.

Thought about that if helped and made things easier to set up.

I previously read that  if you know what you are doing, you can even use an old router as a repeater. I do have a few of those too.

BUT...

I get about as far as accessing IP addresses then in Windows 10 Network and sharing section, get asked for DNS info which leaves me lost.

Most online help said, "just leave DNS as is".

But the settings look like they need something I don't know about.

Appreciate it if anyone has advice, help, link to help that someone without experience like me could understand possibly....

Thanks in advance, APPRECIATE it ! ! !