How can a group of volunteers build at least the tech for a replacement for the internet?

I was hoping that each individual user could run and maintain a piece of the infrastructure in a decentralized grassroots way.

How can users build a community owned and maintained replacement for the internet?

I hope that we can have our own servers and mesh/line/tower infrastructure and like wikipedia/internet-archive type organization and user donations based funding.

How could this be realized?

Can this be done with a custom made router that has a stronger wifi that can mesh with other’s of it’s kind? like a city wide mesh? or what are ways to do this?

Edit: this is not meant as a second dark web but more like geocities or the old internet with usermade websites