That isn't what Aloha was getting at, why is a layer 2 device (in this case a WiFi AP) even interacting with IP addressing? You should be able to run whatever you want, whether that be IPv4, IPv6, or your own custom protocol using raw ethernet frames (of which there are quite a few).

Also, what is this whole "Comcast did not play nice with them" trope? I've dealt with Comcast many times, and used Asus, TP-Link, Cisco (the DPC3010 modems are my favorite) and others with them without issue. They aren't even a factor in your internal network and whether or not IPv4 or IPv6 works in it...

So at home my Comcast connection works fine with most modems and routers without any problems.

At my startup's house:

- Using the Comcast default combined modem+router works.

- Using the Google Wifi AP with a DPC3010 resulted in the DPC3010 being bricked upon connecting to the cable line. This is after the DPC3010 was working fine at my home. That DPC3010 no longer works, even at home, and only gets a power light upon startup.

- Using the Google Wifi AP with a TP-Link modem works flawlessly. No IPv6 though.

- 3 other routers that work at home do not work at my startup's house with the TP-Link modem. Asus RT router gets a fake 10. address from Comcast, Xiaomi router stops responding after several hours, Cisco router gets no DHCP lease whatsoever. All three work at home, all flawlessly.

Comcast is unwilling to debug, saying that unless I use their official combined modem+router they will not provide support.

I still think the combined router/modem is the issue. I've worked with one of the combined router/modems with a Comcast business connection before. Very buggy, and Getting the static IPv6 and IPv4 is a herculean task. The Cisco DPC3010 has its own oddities. I would suggest looking at some of the newer cable modems that Comcast supports. If you need static IPv4 though, you have to use Comcast's equipment.

The combined one works, it's just devoid of features I want, hence the separate modem and router. As for the router the Google one is the only one that seems to work at my startup's place. The other routers I tried only work on my home Comcast line.

Honestly I would ditch the Comcast provided router, and bring your own cable modem and router. I can't count all the number of issues I've had with Verizon and Comcast provided equipment.