The link Axolotl replied with is it. Its a selfhosted server software that you host on one machine and access from others. You access it via its webui on your browser, and it gives you a browser based reader for all your ebook and manga files. The benefit to that is its device independent. You can pick up and keep reading from anything with a browser.

I usually download an epub of the book and put it on my Kavita server, then read from my phone.

The ui still kind of feels unpolished in commet. I tried it out two days ago, but ended up going with element instead. Just felt better to use

Yeah I just set up a synapse + livekit server last night. Voice, video, and screen share rooms work flawlessly