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General Questions

Video stream resolution Data usage Bandwidth required
480p ~1.1 GB/hour ~2.4 Mbit/s
720p ~2.2 GB/hour ~4.8 Mbit/s

Tip: to switch resolution, change the recording resolution in FreeFlight Pro.
If recording is set to 1080p, the live video stream will be 480p (default in FeeFlight Pro)
If recording is set to 720, the live video stream will be 720p
The data rate can be further reduced, but requires some manual scripting.

Note: the data usage will arise on both SIM cards. Hence, you might get charged twice for the data usage mentioned above (depends on your operator).

  • Q: Is it possible to use the softmod just for real-time location tracking via GPS, but not for video/controls/telemetry? (e.g. to save mobile data)
  • A: Absolutely! All you need is to open the Glympse link received via SMS/Push Notification once the Disco is started. As long as the 4G mode is not initiated via double press on Settings, your Skycontroller 2 will stay on Wi-Fi (green LED). Just fly as usual.
    If you never want to use the option for 4G/LTE video/controls/telemetry, you can ignore the following installation steps entirely:
    • A mobile tethering device is not required.
    • ZeroTier account does not need to be created.
    • The following config files do not require to be set:
      • disco/uavpal/conf/zt_networkid
      • skycontroller2/uavpal/conf/wpa
      • skycontroller2/uavpal/conf/ssid
      • skycontroller2/uavpal/conf/zt_networkid
    • /tmp/disco4g/skycontroller2/ does not need to be run (double pressing the Settings button will have no effect)
    • All steps after reboot can be ignored


  • Q: Which Huawei E3372 model is right for me?
  • A: There are different models of Huawei E3372 modems: 153, 210, 510, 607. E.g. E3372h-153 is a very common one. Different models support different LTE bands. This is important as most countries regulate frequencies and therefore only a set of LTE bands is available in certain countries, of which again mobile network operators might only use a subset.
E3372 Model LTE Band supported should* work in
153 and 210 1,3,7,8,20 Africa, Asia, Central and South America, Caribbean, Europe, Middle East, Oceania
510 1,2,4,5,7,28 US (excluding Sprint)
607 1,3,7,8,28,40 Africa, Asia, Central and South America, Caribbean, Europe, Middle East, Oceania, Russia

*This is only a guideline, you should double check our list of Known Working Mobile Carriers and Settings where we recommend specific modem models per carrier. Or check out LTE bands used by your mobile network operator and make sure you buy a model that covers at least one supported LTE band.

Huawei E3372 modems are available in two different flavors, Hi-Link mode (firmware 22.x) and Stick mode (firmware 21.x). Both firmware versions can be found on E3372s and E3372h hardware types:

  • E3372s is slightly older and comes mostly (but not exclusively) in Stick mode.
  • E3372h is newer and comes mostly (but not exclusively) in Hi-Link mode.

A conversion between Stick and Hi-Link mode is possible in most cases, but the process is not straight-forward.

Both types should work with the 4G/LTE softmod. We recommend the E3372h modem with Hi-Link.

  • Q: What does the Huawei E3372 modem's LED indicate?
  • A:
    • Green, flashing twice every 2s: The USB-Modem is powered on.
    • Green, flashing once every 0.2s: The software of the USB-Modem is being upgraded.
    • Green, flashing once every 2s: The USB-Modem is registering with a 2G network.
    • Blue, flashing once every 2s: The USB-Modem is registering with a 3G network.
    • Cyan, flashing once every 2s: The USB-Modem is registering with a 4G network.
    • Green, solid: The USB-Modem is connected to a 2G network.
    • Blue, solid: The USB-Modem is connected to a 3G network.
    • Cyan, solid: The USB-Modem is connected to a 4G network.

  • Q: What happened to the Raspberry Pi?
  • A: Right! In the first Youtube video uploaded, there was a Raspberry Pi required to bridge the connection from the Skycontroller 2 to the tethering device. We managed to find a solution without the RPi.
    RIP RPi! :disappointed_relieved:

  • Q: How much extra power does the 4G/LTE modem consume?
  • A: The Huawei E3372 modem draws 0.10A - 0.15A under full load, whereby the Disco consumes
    • maximum (e.g takeoff): 15.5A
    • average: 3.6A (based on Parrot's "45 minutes" specification)
    • C.H.U.C.K. without motor running: 0.7A

Therefore, the power consumed by the 4G/LTE modems is not significant (less than 5%). Additionally, not fully utilizing the Wi-Fi antennas during a 4G/LTE flight, saves a fair bit of power as well.

Operating Disco over 4G/LTE

  • Q: What if the 4G/LTE connection gets interrupted during a flight?
  • A: Usually when the video stream starts to get choppy, you are approaching a not spot (area with no mobile phone reception, or not enough bandwidth available). If your 4G/LTE connection gets interrupted, your Disco will initiate a Return-to-Home (RTH) after a few seconds. This will normally bring back the connection (video stream and controls). In the worst case scenario that there is no reconnection, the Disco will fly back to the take-off point and initiate auto-landing. It might be advisable to change to Wi-Fi mode as soon as the Disco is in sight so you can take over for a controlled landing.


  • Q: Do I need to reinstall the softmod after a firmware upgrade/downgrade?
  • A: If the firmware upgrade was for the Disco only (and not for Skycontroller 2), you can simply run the following steps
    • Turn on your Disco and connect your PC's Wi-Fi to the Disco (e.g. DISCO-123456).
    • On Disco firmware 1.7.0 and newer: Double press the Disco's power button to enable the telnet server.
    • Open a Command Prompt (Windows)/Terminal (macOS/Linux) and Copy/Paste the following commands manually.
      • telnet
      • mount -o remount,rw /
      • ln -s /data/ftp/uavpal/conf/70-huawei-e3372.rules /lib/udev/rules.d/70-huawei-e3372.rules
      • reboot

Note: all configuration files on the Disco will be retained.

If you upgraded/downgraded Skycontroller 2's firmware, or if the above steps did not work, you should do a full re-installation according to the Installation Instructions. Have a look at this FAQ entry on the steps that can be skipped during the re-installation.

Note: Make sure you set the configuration files in the downloaded and extracted .zip archive again according to your preference.

Additionally, Glympse shows more 4G/LTE relevant data than FreeFlight Pro: the name label (e.g. DISCO-123456) is followed by detailed telemetry data, e.g. Sig:4G/70% Alt:45m Bat:86%/12.09V Ltn:28ms [D]

  • Sig:4G/70% - the mobile signal of the drone's modem. 3G vs. 4G and the signal strength in percentage, derived from the RSSI dBm
  • Alt:45m - the current altitude in meters, relative to the take-off point
  • Bat:86%/12.09V - battery capacity in percentage and voltage (important for some of the Li-Ion battery mods)
  • Ltn:28ms - latency between the controller and the drone (shown in Wi-Fi and 4G mode)
  • [D] / [R] - indication whether the ZeroTier connection is [D] direct (low latency, full throughput) or [R] relayed via ZeroTier's cloud infrastructure (higher latency, limited throughput)

  • Q: Can I just reinstall Disco4G? Will anything be overriden?
  • A: You can simply follow then instructions to reinstall the softmod. There are good reason for reinstallation, we are constantly improving Disco4G, so you might want to reinstall the latest version. Don't forget to set your preferences in the conf files again after downloading the latest version from GitHub, otherwise the existing config files on the Disco and Skycontroller 2 will get overriden with the example files. Note: A reinstallation does not require re-authentication in the ZeroTier Web interface (unless the Network ID has changed in your config file).

Check out our list of Known Working Mobile Carriers and Settings, to see if ZeroTier is able to get a Direct or Relayed connection per carrier.
Glympse indicates whether the current connection is direct or relayed ([D] or [R]).

Feedback via our Slack Workspace (#dev channel)


  • Q: My 4G/LTE connection is slow or unstable: the video stream is choppy and/or delayed and I get disconnected regularily
  • A: Check the following possibilities:
    • Your carrier's coverage might be bad in the area where you are trying to fly, you can use CellMapper or OpenSignal to check for 4G/LTE coverage.
    • It is highly recommended to use both SIM cards from the same carrier for higher performance and lower latency. Also check that you are using the same APN on the Disco and your mobile tethering device (if possible).
    • ZeroTier might be relaying the connection via public Internet, see this FAQ entry for more information.
    • Make sure your mobile tethering device as well as the Disco's modem have a 4G (and not a 3G) connection, see also Huawei E3372 LEDs.
    • Using a single device for the mobile hotspot and FreeFlight Pro can have a performance impact if the device is not powerful enough. Although it's possible, we recommend to use two separate devices, one as mobile hotspot with Glympse and the other one running FreeFlight Pro which is connected to SkyController 2 via USB cable.
    • Some carriers impose a bandwidth cap to tethering data (e.g. T-Mobile USA). Make sure your carrier unlocks the full speed.
    • Run the following two speed tests to confirm there is sufficient bandwidth available:
      1. Plug the modem into a PC and use a browser to run a speed test, e.g. (ensure the PC has all other LAN/Wi-Fi interfaces disabled)
      2. Use a PC and connect it via Wi-Fi to your mobile tethering device, use a browser to run a speed test, e.g. (ensure the PC has all other LAN/Wi-Fi interfaces disabled)
        It's important not to use an App on your mobile tethering device to conduct the second speed test. It will not reveal any carrier imposed bandwidth cap on tethering data.
    • If the connection is lost and does not recovered at all, confirm that you have sufficient data balance available on both SIM cards.

If you have accidentally removed a member in the ZeroTier Web UI, it will be blocked from joining. You will need to remove and then reinstall the softmod again, so that the Skycontroller 2 and the Disco gets added as new members again (of the same Network ID).

  • Q: I did not receive the SMS with the Glympse link to track my Disco's location, anything I can do?
  • A: Make sure the USB modem is successfully connected (blue or cyan solid LED on the modem)
    • Some SIMs are "data-only" and don't allow you to send SMS. This is a restriction imposed by your mobile network operator.
    • Some users have reported it worked when omitting the international prefix or just the "+" in front of the number in the conf/phonenumber file.
    • The phone number in conf/phonenumber should be the device where you want to receive the SMS with the link (and not the Disco's SIM phone number itself).

      Note: As alternative to SMS, you can also use Push Notifications to receive the Glympse link. Have a look at the Installation Guide.

  • Q: Skycontroller 2 is trying to connect to a tethering device such as an iPhone, it keeps flashing magenta for some time and is then falling back to green (Wi-Fi mode).
  • A:
    • Make sure you set the config files ssid and wpa correctly.
    • For iOS: the curly apostrophe (single quote sign) in the Hotspot's name can be an issue, e.g. "Name’s iPhone". Quick fix: remove any special characters (e.g. "My iPhone"). This can be done in Settings → General → About → Name. If you want to use the straight apostrophe sign (e.g. "Name's iPhone") instead, you need to rename it in iTunes as the iOS keyboard does not offer straight apostrophes.
    • For iOS: if Personal Hotspot was activated for a long time, it stops broadcasting itself. This is a known iOS issue. You might need to disable and re-enable Personal Hotspot, or even restart your iOS device.

  • Q: How can I debug issues on the Disco?
  • A: You can connect your PC via Wi-Fi to the Disco and telnet into
    On Disco firmware 1.7.0 and newer: Double press the Disco's power button first to enable the telnet server.
    By running the command ulogcat | grep uavpal you see the log messages created by the softmod.

  • Q: How can I debug issues on Skycontroller 2?
  • A: a) Make sure your Skycontroller 2 is connected to the Disco via Wi-Fi (green Power LED on the controller). You can first connect to the Disco (see above) using telnet and run /data/ftp/uavpal/bin/ to hop on to Skycontroller 2.
    b) You can directly connect from your PC to Skycontroller 2 using a USB Ethernet adapter on Skycontroller 2 connected via Ethernet to your PC. You need the tool adb which is freely available for all major OS platforms. The Apple USB Ethernet Adapter (MC704ZM/A) is known to work.
    By running the command ulogcat | grep uavpal you see the log messages created by the softmod.

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