What is the right sequence for pairing a RTL510 and UT800?

Please view our FAQ here on the light network settings. 

You will not need to pair these two in any specific order. 

Thanks! When I click on the link, I get an 'Access denied' error

I cannot access the link either, but I would say remove any existing light pairings and remove the radar if it is paired as a  radar.

Put the radar in pairing mode and add it as a light. This will also add it as a radar sensor.

Next add the UT800.

Thanks for the tip. If I add just the RTL510 to my Fenix 6 also (to get vibration alerts for approaching vehicles), will it also get automatically added as a light also on my Fenix and will that mess with how the lights interact with the Edge?

In my experience it is not possible to have the fenix and edge paired to lights at the same time and have the lights stay in "automatic" mode.  Every time I enable the lights on my Fenix it sets them to "individual" mode and even when I set them back to auto, they just reset themselves back to individual shortly.

I haven't tried enabling only radar on the Fenix, but if that's possible there's a chance it might not muck with the light network, please report back your findings.