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@jennifer/routeros

LTE / cellular

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

Background

A cellular modem gives the router a mobile-broadband uplink - the classic backup WAN (fail over to LTE when the wired line dies) or the primary link at a site with no wired internet. Two things determine whether it works: the APN (the carrier's access-point name, from the SIM's provider) and the signal (placement and antenna). This topic reads the interface, measures the live signal, and sets the APN; returns empty on routers with no modem.

Structs

jennifer
mt.LteInterface { id, name, running, disabled, comment }
mt.LteStatus {
    status, registered,          # registered computed from status
    operator, accessTechnology,  # "lte" / "5g" / ...
    signalStrength, rsrp, rsrq, sinr
}

Functions

FunctionPurpose
lteInterfaces(c) → list of LteInterfacethe modem(s), empty if none
lteStatus(c, name) → LteStatuslive registration + signal
setLteApn(c, name, apn)set the carrier APN
enableLte(c, name) / disableLte(c, name)up / down

Examples

Is the cellular link healthy?

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);
if (not $s.registered) { io.printf("not on the network - check SIM/antenna\n"); }

Set the APN (the usual "registered but no data" fix):

jennifer
mt.setLteApn($c, "lte1", "internet");

LTE as a backup WAN, in one picture: give it a route with a higher distance than the primary (routing.md), masquerade it (nat.md), and let distance-based failover switch to it when the primary gateway dies - optionally watch the primary with netwatch.md.

Pitfalls

  • Signal reality check: RSRP better than about −90 dBm is good, −100 to −110 is marginal, worse drops out. An external antenna and moving the router to a window fix more than any config.
  • APN comes from the carrier - a wrong one registers on the network but passes no data. Some SIMs need a username/password too (generic verbs on the APN profile).
  • Data caps: as a backup, make sure normal traffic doesn't silently ride the LTE link (check the route distances) or a metered SIM burns through its cap.
  • 5G/technology and band locking, SIM PIN, and roaming are set via the generic verbs on the interface.