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LTE / cellular

File: src/topics/lte.j. Paths: /interface/lte (LTE_PATH), /interface/lte/apn (LTE_APN_PATH).

Reference: cheatsheet.

A cellular modem gives a backup WAN, or the only uplink at a site without a wired line. It needs the carrier's APN and enough signal.

lteInterfaces returns an empty list on any read error: on a router without a modem, and also on a dropped connection. lteStatus runs monitor once; registered is true when the status contains "registered". setLteApn creates or updates an APN profile named routeros-<interface> and binds it to the interface.

jennifer
def s as mt.LteStatus init mt.lteStatus($c, "lte1");
io.printf("%s on %s (%s)\n", $s.status, $s.operator, $s.accessTechnology);
io.printf("RSRP %s, RSRQ %s, SINR %s\n", $s.rsrp, $s.rsrq, $s.sinr);

mt.setLteApn($c, "lte1", "internet");   # fixes "registered but no data"

As a backup WAN: give the LTE route a higher distance than the primary (routing.md), masquerade it (nat.md), and optionally watch the primary with netwatch.md.

Pitfalls

  • RSRP better than about -90 dBm is good, -100 to -110 dBm marginal, worse drops out. An external antenna or a window position helps more than configuration.
  • A wrong APN registers on the network but passes no data. SIMs that need an APN user and password: set them with the generic verbs on the profile.
  • On a metered SIM, check route distances so normal traffic does not use the backup link.
  • Band and technology locking, SIM PIN and roaming: generic verbs on the interface.