There’s this Polish Aero2 mobile network provider that offers a free, unmetered 512 kbps data plan, which is perfect for use as a backup link for your home router/server. And while my rather obscure, $10 Huawei USB LTE modem works out-of-the-box with Linux and NetworkManager, I struggled for quite a while to get it running under the FreeBSD-based OPNsense firewall. Turns out the modem’s peculiarities required a deep dive into tracing USB communication and its protocols to eventually get it initialized with a one-line command sending a raw USB message to device.
