I’m sorry for your loss, loosing loved ones are never easy.
Try this cable from your modem to your M3. You’re very likely to hear audible improvements over generic 25FT cable. The 22AWG version is bit stiffer so no sharp bends. The 26AWG version is more flexible. I am using 22AWG version and I’m extremely happy with the sound.
https://www.amazon.com/gp/product/B089N94XXV/ref=ox_sc_saved_title_8?smid=A1EA54VWB150Z7&th=1
I thought about fiber option (due to long distance) but at this cost, the LINKUP is a no brainer. I am using a 50FT run from my modem to a switch next to my setup.