Slow speeds
Check which band you are connected to. If your router admin interface shows 4G LTE rather than 5G NR, you are not on 5G at all. This may be because 5G coverage is insufficient at your location, or the router has fallen back due to weak signal. Check signal metrics (RSRP and SINR) and consider antenna repositioning or an external antenna upgrade.
Check for peak-time congestion. Run speed tests at 9 AM, 1 PM, 6 PM and 11 PM. If speeds are significantly lower at 6-9 PM, cell site congestion is likely. This is a network capacity issue and cannot be resolved by changing hardware. Switching operator or SIM may help if an alternative network has better capacity at your location.
Check SIM fair use status. Some SIM plans throttle speed after a monthly data threshold. Log into your operator account or check the router’s data usage statistics to confirm you have not exceeded any threshold.
Dropped connections
Check signal quality (SINR). A consistently low SINR (below 0 dB) suggests interference or a very weak signal. Repositioning the CPE or moving to an external antenna often resolves marginal signal issues.
Check for SIM authentication issues. If the router logs show frequent de-registration events, the SIM may be having authentication issues with the network. Try the SIM in a phone to confirm it connects and stays connected. If it drops in a phone too, the issue is with the SIM or operator account rather than the hardware.
Check router firmware. Outdated firmware can cause instability. Check the manufacturer’s website for updates and apply them. Teltonika and most industrial router brands release regular firmware updates.
Cannot connect at all
Verify the SIM works in a phone first. If it does not connect in a phone, contact your operator. If it works in a phone but not in the router, check the APN configuration (see installation guide above), check the SIM is correctly seated and the right size for the slot, and check that the router supports the bands your operator deploys.
Inconsistent performance
Variable performance that does not follow a time-of-day pattern suggests a physical signal issue: the router is near the edge of reliable coverage, and signal fluctuates with minor changes in radio conditions. An external antenna with higher and more stable signal capture is the solution for this class of problem.
CGNAT preventing remote access
If you need to reach equipment at your 5G FWA site from a remote location and cannot because of CGNAT, options include: switching to a SIM with a static IP, using a VPN service that provides a fixed endpoint (Wireguard VPN on an outbound connection works behind CGNAT), or using a remote management platform such as Teltonika RMS that is designed to work without a static IP.