By the way, my general tips on improving Zigbee network range which might relieve issue with delays:
- Add more Zigbee routers between the far away devices and the next nearest router, distributing more Zigbee routers around areas with poorer reception. Zigbee network topology uses a “mesh network” design which means that each device that acts as a Zigbee router will extend the range of your Zigbee network. While there are exceptions, as a rule of thumb, almost all permanently powered devices will serve as a router. This is a part of Zigbee design concept, simple add more powered permanently Zigbee devices to get better coverage, (there are purpose-specific Zigbee routers which you can find by doing a community search for “Zigbee signal repeater” or “Zigbee range extender”). Devices that can not act as routers are known as “end devices” and you should know that some end device models from brands like Xiaomi/Aqara have issues connecting through routers.
- Utilize a USB extension cable to move Zigbee coordinator adapter and place your Zigbee coordinator adapter in a sensible position, away from WiFi access-points/routers or other sources of 2.4GHz signals in a location that it is relatively free from strong signal interference. The best location will depend on your building’s floorplan though normally you want to place it somewhere in the middle. Building materials are also very relative as example dense/thick concrete, bricks, masonry, etc. dampen will all wireless signals and therefore it is best to place your Zigbee coordinator adapter some distance from walls, ceilings and floors. You could also try different orientation of your Zigbee antenna (or your whole Zigbee coordinator adapter if it has an internal antenna). This is because the connection between the Zigbee coordinator radio and your other devices also depends on the way the antenna oriented in space. Note! A bad USB extension cable may lead to connection issues between the system and the Zigbee coordinator adapter, symptoms of this are disconnection messages.
- Check your WiFi access-points/routers channels in use to see if your router/access point is overlapping the channel your Zigbee network is using. If so change the channel of the access-points/routers and lock it. It will normally be easier than changing the channel of your Zigbee network and then you will have to re-join/re-pair all of your Zigbee devices. A busy WiFi access-points/routers that are operating the same frequency range (overlapping channels) as your Zigbee coordinator will drown out the Zigbee traffic, and even more so if they are located close to each other. See this article for WiFi and Zigbee channels coexistance to avoid using overlapping frequency ranges.
- Update the firmware on your Zigbee coordinator adapter and your Zigbee devices. Note that depending on your hardware the latest Zigbee coordinator firmware might not always be the one recommended by the community so it is advised to ask before upgrading.
- If you Zigbee coordinator adapter a removable antenna with an SMA-connector then you have the option of buying a high-gain antenna as an upgrade. In addition, you also have the option to use an antenna extension-cable if needed (though for various reasons that is not a good alternative to only using a USB extension cable with your Zigbee coordinator adapter if possible). This should really only be needed if you are trying to cover a long distance, like to another building or very dense/thick walls, ceilings and floors.
- Buy more powerful Zigbee radio hardware with better radio range, preferably with an external antenna. If you are not only experimenting but want a permanently stable and healthy Zigbee network with potentially many devices then you should consider upgrading to a more powerful Zigbee coordinator USB adapter. Generally, those with an external antenna will have better range, therefore you will also want to avoid buying an internal adapter unless it has an external antenna.
The fact is that bad signal reception can be due to many different things and experienced Zigbee users in the community will normally advise that there are a few simple fundamental things that you should really attempt to do first in order to better optimize your Zigbee devices equipment which can resolve many basic problems related to signal strength or interference issues. Note that there are always exceptions, however, if possible to try to follow at least some of these general recommendations before you take more advanced steps like reporting issues to developers and submitting debug logs. Just following these simple tips below should help improve signal strength and reduce signal interference which can normally many problems with a Zigbee network.