Losing connection to Varia RTL510

No idea as to what is causing this but I experience a similar problem with my RTL515. During a 2 hour ride there will be 2-3 occurrence when it will say lost connection to radar for about 10-15 seconds or so and then reconnect. Hope this is sorted with the forthcoming firmware update but I don’t see any mention of this in the release notes. 

Yes I too would like this fixed.

Same here. RTL-510.

Same here. RTL-510 and Edge 830. I tend to notice it happening primarily during group rides. In our group, we usually have multiple people with Varia RTLs and Edge devices. I am not sure if it is just the multiple rider thing or if it is due to some type of interference between the various RTLs and Edge devices.

Happens to me all the time too.  At least two or three times per ride, the radar disconnects, I get the warning and beep, and then after a few seconds it seems to reconnect.  No idea what causes this.

I have the same issue, but it seems all sensors get disconnected, I see my speed sensor drop at the same time then come back.

This has been going on since two updates ago.. horribly annoying and distracting.  I ride in good size groups 12-30 people and we'll have dozens of disconnects on every ride and it's happening to everyone with Garmin's, from 5 series to 10 series, all of them are having this issue.  But not Wahoo people users, they don't get drops like us... which means it's 100% a Garmin Edge software issue.

We noticed it happens primarily during hills when separation occurs which led us to experiment on why. As a result, we landed as caused by the broken "light network" concept Garmin attempted to do but never got to work and they never followed up with cleaning up the code, so there's still junk code running.  It seems Garmin wanted lights to talk to one another, so they implemented forming a light network, but then never bothered to make the light network actually do anything and it's lights and radars joining and dropping from your light network as people come in and out of range of your Edge.

As a result we've narrowed it down to be that YOUR light is not disconnecting from YOUR Garmin.  it's your co-riders light disconnecting from YOUR Garmin's useless light network which triggers a "Radar disconnected" message and a beep.. which of course we all interpret as my light disconnected from my network.

Garmin just needs to kill the alerts when someone's light disconnects from your own Garmin. who cares if Bob's light isn't talking to my Edge... I don't know why my co-riders light is connecting to my Garmin to begin with, especially if it's not actually providing me any notifications about cars or serving any purpose whatsoever.

I suspect like the majority of Garmin bug's they will be here for many years to come.

I think your issue is different than the light issue.  Since two versions ago, the same time the light issue started; they broke the ANT+ sensor stability... it's completely messed up.  devices disconnect all the time. for SRAM power meters they have 5 second drops every 45 seconds. I have a speed & cadence combined sensor, and speed stays, but cadence drops data constantly which makes no sense.

This was happening to three of us, one guy tried switching his sensors from ANT to Bluetooth and tada! perfectly working sensors with no drops... I did the same, perfect, not a single second of dropped data, no disconnects.

Does your sensor support bluetooth? if so, switch to that. you'll find everything works much better.

Are these disconnect issues still happening?  Was about to get an 830 and was looking at the RTL515 as well

Yes. One or two are common mid-ride. It resumes in seconds and warns when not connected. It is wireless and more sensors and phone are connected, so I do not expect miracles here. Not just Varia but also other sensors disconnect. Phone not so much (very rare) using livetrack. 
versions 9.1 and 9.26 beta. Previous versions also had issues. One learns to live with such limitations for the peace of mind of the system. It never once gave me a false negative. Some minor false positives, but not one false negative in 2 years and more than 40’000km.