Zigbee limits are based on the amount of memory, but you shouldn’t run into them before you hit the general smartthings limit of 200 devices per location. And that includes all type of devices, Zigbee, zwave, LAN, cloud to cloud, and virtual.
But to be honest, the offline problem is one that affects many people with many different types of devices and just seems to be a legacy of the groovy cloud platform. Hopefully the new edge architecture will work better in this regard.
With regard to your questions about modifying the device type handler to shorten the check in time, if you are using custom code, you need to find the discussion thread for that specific DTH and ask there.
The 64 limit is only for Zigbee devices that are currently connected in one hop to the hub. If your Devices route through other Zigbee devices on the way to the hub, then there’s no fixed limit for Zigbee devices.
The option is just to add more zigbee repeaters if you need them. That includes most mains power devices except for the sengled brand.
Zemismart battery operated devices will not act as repeaters, but their mains powered ones usually will. And so will the lightbulbs as long as they have power, although they aren’t always really efficient repeaters.
There is no Edge X groovy that I know of. Edge is based on a different programming language, Lua, and it was released in beta about a month ago. A number of community members have been writing edge drivers (the new platform’s replacement for DTHs) and you can try one of those if you like.
And you can find links to the edge drivers that have already been written by community members in the community – created wiki,
There’s a link in that thread you can follow to install the edge drivers. You can go back to Groovy by deleting the devices, deleting the edge driver, resetting the device and re-adding it. Samsung TVs and appliance connect direct to the smartthings cloud, so they don’t run on Edge.
Do you leave your bulbs powered on 100% of the time? I.e. never turn them off from the wall switch? Also, is your hub at least 5 feet away from any Wi-Fi access points?