Slow download but ok upload

Hello again,
I’ve been recently having an issue with 2 ROV’s where they are running into an acceptable upload of about ~42mbps but a rather poor download of 18-22 mbps, with one having visible dropouts on the download which looks like this

Has anyone run into this and knows how to fix it?

I’ve currently tried bypassing the ethernet switch (checked to make sure it wasn’t one with the faulty part already) from the ROV, putting in a new fathomX, different tether, tether on other machines works fine.

Hi @Qlowe,

A few questions to clarify:

  1. Are you having noticeable issues when operating the vehicle?
  2. Which BlueOS version are you using?
  3. Which Raspberry Pi type are you using? (e.g. 3B / 4B)
  4. Do you have multiple high bandwidth devices active?
    • The Network Test shows available bandwidth, so if your control computer is downloading multiple video streams, and data from a high resolution imaging sonar (for example) from the Raspberry Pi then it’s expected the available download bandwidth is lower than it would otherwise be
  5. Did any of the things you’ve tried help?


  1. Currently the machines occasionally lose heartbeat. I think its due to the download almost completely dropping out.
  2. I’ve tried 1.0.1, beta 9 and beta 16 on them
  3. Honestly not sure off the top of my head for one of them, the other is a 3B i think and i don’t currently have access to check them, is there a massive difference between?
  4. I’m not using a sonar, one machine does have a DVL on it and a secondary camera (with navigator), but the other is just a standard bluerov2 (With a pixhawk, with the raspberrypi 3B). If i disconnect the cameras or turn off the streams i do gain more bandwidth but it is especially low on the bluerov2 compared to other ones i have tested.
  5. Not currently. I’m looking at ordering a higher bandwidth version of the fathom X but it is larger - also the fact that it doesn’t seem to be the case of the other bluerov2’s with the same 300m makes me unsure if that is going to fix anything.

4B has additional processing power, and a dedicated ethernet controller. 3B shares its ethernet controller with its USB controller, so can have reduced network capacity if there’s significant communication with connected USB devices at the same time.

Navigator only works on a Raspberry Pi 4B. A DVL shouldn’t use much bandwidth compared to a camera, and a secondary camera shouldn’t cause significant issues unless it’s a high resolution/framerate and/or uncompressed stream.

If bypassing the tether with a directly connected ethernet cable didn’t help then I don’t expect a higher bandwidth HomePlug module would either - that seems like an issue with either the Raspberry Pi or your topside computer’s software or networking hardware.