I’m sure that’s frustrating! Routing corrections can be really tricky. After you had the lamps in place, did you unplug the smartthings hub for 15 minutes and then plug it back in? You need to get the garage door to know that it has new neighbors or it won’t use the repeaters. Unplugging the controller (in this case the hub) and leaving it off-line for a while will cause all the devices to look for new routing information.
Once you do you plug it back in it’s not like you see in instant improvement. It takes a while for the routing table changes to propagate. Typically we would leave everything in place and come back the next day and check them to see if we were getting better routing.
Also, you have the Osram lights connected directly to the hub, right? Not through a bridge?
You can also try try taking device that you know repeats, like a plug-in module or the first generation smartthings motion sensor (on USB power, it won’t repeat if it’s on battery) and put it near where you want to put the bulbs. Again, unplug the controller for 15 minutes, plug it back in, and wait to check QOS improvements until the next day. If you don’t see any improvement with a known repeater, the bulbs aren’t going to be able to help either.
Then the problem is likely either a bottleneck, local interference, or maybe a bad end device.
You might have a bottleneck somewhere on the network. It could happen, depending on the order in which you added devices. Because zigbee devices choose their own parents based on signal strength, it sometimes happens to many devices try to pick the same parent, and the network becomes inefficient.
One way to fix that is to power off not just the hub but all your zigbee devices. You not going to have to rejoin them to the network, just unplug them or kill the power on that circuit.
Leave everything off for 15 minutes.
Now plug the hub back in and leave it on for five minutes.
Now return power to all the mains-powered devices, beginning with the ones closest to the hub and working out.
Again, be patient. Check the next day to see if you got visible message chain improvements.
Well, those are just some things to try that don’t require specialized equipment. Good luck!