I have several Sonoff plugs scattered around the house as well as Philips and Sengled bulbs. They're all Zigbee.
I have sensors that have stopped reporting.
How do I check how they are routing back to HE? Can I change the route for more stability?
If you are concerned about sensors that have stopped responding, the best thing to do is do monitor their "Last Activity At" data and see how it compares to your expectations. (For example, most of my sensors report at least some activity once or twice a day, even if it's just a battery report and it's something like a motion sensor in a room that didn't receive any actual motion.) I'd guess that most people who do this do it with a custom app (Device Watchdog and Device Activity Check are the two most popular ones I'm aware of; I wrote the latter). However, you could also create a Hubitat Dashboard with the "Last Updated" template for all the devices you care about and just scan that Dashboard on occasion yourself to see if anything seems off.
Some people also monitor battery reports (there are built-in and custom options for that; much more flexible options if you go the custom route), but these are notoriously unreliable. Like many others, I'd suggest monitoring activity vs. expectations instead.
Finally, to get back to your first question: you can't manually assign or change routes. Zigbee devices should automatically find good routes for themselves. Your Sonoff plugs are "repeaters" (or "routers" in Zigbee terms) and should contribute to a strong mesh. Unlike most mains-powered devices, your Sengled bulbs are not repeaters. So, like your sensors, they'll rely on a good mesh of other repeaters to have a reliable route back to your hub. Your Philips Hue bulbs are repeaters, but many Zigbee bulbs (including these, possibly only certain generations) have been reported to be poor Zigbee repeaters, "eating" messages once in a while instead of passing them on like they should.
So, on the topic of your sensors not responding, my first guess would be the easy one--a dead battery. But if that's not it, my second guess is the Hue bulbs (and it's probably not a bad issue to address regardless). Many people avoid this problem by keeping Zigbee bulbs on a separate network, whether it's a Hue Bridge or a second Hubitat hub. Hubitat has a built-in Hue Bridge integration and a couple community options (one of which I, again, wrote), which most people find to work well, but either way would avoid this potential problem.
To add to what @bertabcd1234 You can press the button on the sensor to force a wake up and see if it's reporting in the live logs. If not, attempt a re pair (do not delete it from Hubitat, it will slot back in as a previously discovered device).
If that isn't working, then as @bertabcd1234 mentioned, it's likely a dead battery. Insert new battery and see if it connects. If not, reset and re pair (again do not delete from hubitat) and seperate your sensors from any ZLL based repeating bulbs you have.
Thanks for the information.
I noticed that if I remove the battery and replace it with the same battery. It would work for a few days They're iris door and window sensors.
Ill try the hue bridge option.
Yeah move all bulbs to the hue bridge, for your ZHA bulbs on hubitat, get some more zigbee repeaters. You can never have too many! Especially with battery edge devices (they don't repeat). You can leave the sengled on hubitat as they don't repeat though.