How to seal hole from bundle of ethernet cables running through wall/floor?
Conduit &amp; Patch Panel

If you're patch panel is embedded in the wall, you might need some additional structural support around it. I would make 2 runs of 2" conduit down to your crawl out of the patch panel. The reason for using conduit rather than just plain wires is that it makes a more finished result and will be easier to add new wires/remove  wires in the future. It'll also be easier to seal it with fire resistant caulk. Once you get into your crawl, you can just put a bushing on the end to terminate the conduit and run your Ethernet freely. Ethernet is low voltage which allows you to run it how you see fit. However, my recommendation would be to use zip-tie tags to group the cables together by room and use the label to notate which room the cables lead to. You can keep the cables up off the ground with zip-ties with screw mounts. However, it's critical not to over tighten the zip ties as it can damage the cable.

Fire Block

Most places require that all holes between levels of a building be sealed with some fire block. There are several different methods for this, but probably the easiest with fire-resistant caulk. Basically, the job of the caulk is to seal off the cavity so that the fire in one area cannot use the small holes in the cavity to pull air from to fuel itself. When the caulk is heated up, it expands in the hole working to keep a consistent seal. Another purpose is to prevent the fire from spreading up the wire.