My latest project is building a combined travel router-firewall and miniserver. It’s based on PC Engines APU2 (specifically apu2d4) embedded platform running either pfsense or OpenWRT. Turns out that there are fewer and fewer miniPCIe form-factor LTE/5G modems, so I’m experimenting with an m.2 to miniPCIe adapter to see if an m.2 cellular modem could be an option. Physically the adapter just fits!
Notes to self: M.2 and miniPCIe carry both PCIe and USB in the same physical connector. The APU2 mPCIe slots 1 and 2 support PCIe 2.0 and USB 2.0. An LTE modem using USB 3.0 data link must be able to fall back to USB 2.0 gracefully or it won’t work. Aside from improved frequency band support, anything beyond LTE Cat 6 card is wasted unless it uses a PCIe data link. It’s possible that PCIe-based LTE/5G modem can work at full speed; possibly worth experimenting if not too expensive.
