Cellular Problems - ZyXEL Communications NR Series User Manual

37.4 Cellular Problems

The SIM card cannot be detected.
Disconnect the Zyxel Device from the power supply.
1
Remove the SIM card from its slot.
2
Clean the SIM card slot of any loose debris using compressed air.
3
Clean the gold connectors on the SIM card with a clean lint-free cloth.
4
Insert the SIM card into its slot and connect the Zyxel Device to the power supply to restart it.
5
I get an Invalid SIM card alert.
Make sure you have an active plan with your ISP.
1
Make sure that the Zyxel Device is in the coverage area of a cellular network.
2
I get a weak cellular signal.
Find the location of your nearest cellular base stations, then install the Zyxel Device towards the direction
1
of those sites. The nearest site or site with a direct line-of-sight is usually preferred.
Note: It is best to test towards more than one cellular site, as the nearest site / line-of-sight is
not always the best due to the terrain, interference, density of usage, and so on. All of
these factors influence the stability, availability and throughput of the link to the Zyxel
Device
Position the Zyxel Device towards a direction where coverage is expected (example the nearest town).
2
Conduct test measurements using the Web Configurator's System Monitor > Cellular WAN Status screen
3
to obtain a report of the cellular network signal strength and quality at various test positions.
Note: It is best to reboot the Zyxel Device before each test measurement is taken to ensure
that it is not camping on the previous cellular site. This is because the Zyxel Device can
'lock' onto the previous cellular site even when the new cellular site is at a much better
signal level and quality.
Although installing the Zyxel Device as high as possible is the usual rule of thumb, it is sometimes possible
that the Zyxel Device is in a weak coverage spot at that specific height. Adjust the height to achieve the
best service possible.
Chapter 37 Troubleshooting
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NR/FWA Indoor Series User's Guide
325