Seeing you have plenty of devices I might assume you weren’t keen on doing a full zigbee reset with V5 firmware? That is a last resort option because you’ll need to add all Zigbee devices again and fix all your flows, but it did help a lot of others, including me, fix these kind of problems. You can also pick a diffferent Zigbee channel then that sits well with wifi routers in your neighborhood. Changing chanels may be possible on a running Zigbee network, but that is device dependent.
So for the other options to try first: Adding a device list is really helpful, so thanks. It seems like you added enough routers before adding sensors, so that in itself is ok. But still it looks like a lot of devices connect straight to Homey, which is limited to around 15. The rest must go through routers.
Aqara sensors are really reluctant to change their initial route though, so I think your problem is that direct connections are full. You do own a lot of Zigbee, so you may be running into limits as routers are also limited in how many they will route for, and also the amount of router “hops” is limited. A hue bridge will max out at 50 devices before you need an extra bridge, and you are over that.
Are you still pairing devices close to Homey (the firmware V4 advice) or in the place they re intended (strongly advised for V5 and onward)? Far away may work better in your case.
There’s also a trick that seemed to work for me if pairing through other routers isn’t working: Shortly after a Homey PTP I have at times more success pairing. I’m no expert, but The way I imagine it is that as after a reboot not all direct connected devices have communicated with Homey yet, so not all slots in the Zigbee chip for direct connections are in use, so it wil pair directly too.
After pairing the devices will need to find alternative routes when direct connections are all full again, but for me that happened on its own.