It depends on the data but usually I'm just never offline. My NAS is accessible from around the world for my music and code repo and since I'm on IPV6 I didn't even have to deal with port forwarding and reverse proxy nonsense. Photos I'm hosting an app that's similar to Google photos and backs up from phone (it's kind of custom to how I do things but there's various self hostable apps). If I know I'm going to be truly offline unable to even connect through my phone somehow I'll manually copy the files to my laptop. I haven't done that in like five years though and it's only been a mild inconvenience once and honestly I just disconnected and enjoyed a peaceful offline day.