Net Neutrality wasn't considered much of an issue back then, it was just taken for granted (and the administration at the time was attempting to enforce it as vigorously as possible).

Forcing independent internet technical infrastructure off the internet and through their own proprietary infrastructure would be the opening shot you would expect if they wanted to open that battle. After all, you gotta boil the frog slowly, and nobody but a tiny minority of technical users would really care about not being able to use third-party DNS servers.

I've never seen or heard of a Cisco router doing anything that would interfere with access to 1.1.1.1.

Their wireless LAN controllers on the other hand, use 1.1.1.1 as the default (but entirely configurable) Virtual IP to use as an anchor for the captive portal.

If you can't access 1.1.1.1 behind a Cisco router it's likely because someone set it up incorrectly.

My Spanish ISP (Vodafone ES) doesn't block external DNS at the ISP level. However, the router they give you:

1) Blocks outgoing DNS requests from the internal network by default. This can be disabled.

2) Doesn't let you specify any other than Vodafone's DNS servers on the DHCP Server configuration. This cannot be changed.

I'll let you decide whether this is blocking or not...