I've actually had something similar to this happen to me before, and the answer is I suffer lol. If it happened again, I'd probably keep myself busy with studying or housework to pass the time.
I think I'd also suffer aha. But besides that, I'd probably be trying to draw something, browsing the internet (via 4g) or playing games, new and old.
This is me almost all the time (best way to avoid windows updates, don't be online). I generally just play offline games like Pokémon or write my stories if I'm not swamped with work.
Knowing that the internet can be a literal hell (*cough*Jake Paulers*cough*), I should be grateful that I don't need to face such monstrosity.
I would probably draw, play piano more often, do puzzles, start a new sewing project, read books, and finally get around to some world building for my original story...Wow, I never realized how many offline hobbies I have. Maybe I should start spending less time on my computer.
I'd probably be sleeping for the most time. For the times I'm not sleeping, I'd practice my cooking skills, read books, play offline Videogames and doing lots of stuff that already had to be done, but isn't because I was too lazy to do it earlier.
Read, draw, and play some Switch games. One of my games require online, but it has an offline singleplayer as well.
All those video games I could probably finish if I didn't have net for a week, I could finally cross things off my list.
Welp I would do non-online video games, draw, ride my bike, hang out with friends, exercise lol, and other tings