Please help me think out adding Pi-hole to my parents Xfinity setup

This is a cross post from the P-hole Sub-Reddit.
Let me start by saying that I LOVE THE PI-HOLE SERVER! Now, I'd like to add one to my dad's house, BUT he is on Comcast Xfinity and only using their provided WiFi Router/Gateway (I ain't calling it a modem). Now the Xfinity setup doesn't allow you to setup different DNS servers, and I'm not sure if it would allow me to use a different DHCP server.
Let's assume I can't change the router to use a different DHCP server. Am I stuck at this point and I wouldn't be able to add a Pi-hole to "protect' his network?
Let's assume I can change the router to support a different DHCP server. The Raspberry Pi Zero W has more than enough processing power to provide DHCP and DNS for his house, but it's not wired and wired is better. I'm pretty sure I could power the Pi Zero W off the USB ports on the Xfinity router and have a small clean install and it's CHEAP.
Some questions I have though:
Could I remote SSH across the internet to admin the Raspberry and Pi-Hole? Should I avoid that and just SSH locally after connecting to dad's network through TeamViewer (that's how I help him now)?
Those of you with Pi-holes and NOVICE users (kids, marketing people) do you hear much complaining when ads get blocked?
My solution has to be stable and K.I.S.S for my parents and the other family members. How long has your Pi-hole been running without you touching it? (I am a nerd and can't keep my fingers off the keyboard)
Thanks in advance for your input! It really helps me work out ideas.

If it won't allow changing DNS, then as you mentioned, it's worth finding out if you can tell the router to use another dhcp server (pi-hole). The alternative to (not being able to) configuring router's dns is to (manually) configure static IP configs for each device that you want pi-hole ad blocking. Not exactly K.I.S.S., and I wouldn't do that even for myself, if not for parents.

I am signed up with comcast xfinity and there is a spot in the lan settings under the router setup page that has dns settings.

Once i had tried ticking off the dhcp server for the router and ended up not being able to access the router page.

This is all with an arris surfboard ac1750.

Aside, my pi b+ is running pihole just fine whille having it connected by ethernet to the router.

I am not at all tech savvy, but i mean, you have the option to use the reset button in case things dont work.

It is optional to make pihole the dhcp server - you could change the router DNS to the pi hole IP (both if two entries) and it should work.

If you can afford it, honestly buying them a separate router and modem would be better in the long run anyways.

  1. More flexibility in terms of configuration.
  2. Comcast charges them a rental/leasing fee monthly ($10) for usage of the modem/router box.
  3. Better hardware.
    If interested I'm currently using a LINKSYS CM3008 and a Linksys WRT1200AC. (The CM3008 I believe actually comes with a guide for setup specifically with comcast)

If the expenses are simply not preferred then yeah you'll have to look into having the pi-hole serve as the dhcp. Just make sure that the dhcp range the pi uses is within the same address space of your router.

ipconfig /all in command prompt will give you just about all the information you'd need to know.

I second the advice to buy a separate router and place it behind the providers router. This is the setup I use. This gives you full access and -control to all settings you need.

You can open the NAT and firewall to access your parents router and pi-hole across the internet. But please ntoe that if you can access it, other can too. Personally I would not do this. IF you do this, I recommend using a VPN server to secure/encrypt your traffic.

I have no complaints whatsoever when using Pi-Hole (three weeks now). The only problem I got was long load times for some sites with pi-hole enabled. And that was attributable to blocking port 80 to the pi-hole in the routers firewall.
Pi-hole is relatively care free. But you should spend time every month to update the PI servers operating system and install new pi-hole versions.