

If you want a novel but obsolete portable storage format, you could check out MiniDiscs. You’d need a working recorder that supports Hi-MD for data storage.
I believe them to be more reliable than Zip discs, though I no data to back that. But still, it’s 20+ year old equipment with mechanical components, so equipment failure is just a matter of time.
Working recorders can also be a bit pricey.










Not a redundancy option, but I also had my routing setup go in to a bad state while traveling which was a hassle.
I solved this by setting up nightly reboots while away. Both my routing PC and modem are rebooted by smart switches (zwave/ZigBee) controlled by home assistant. Which means they’ll operate without a working network. The routing PC is set to shutdown one minute before the smart switch turns off, and set to boot automatically when power is restored (smart switch turns back on). Which avoids any issues with hanging on a reboot.