I just ordered my first three of the popular Tuya USB Repeaters for a total price of under $35CDN/shipped (11.11 Sale) from this store:
https://www.aliexpress.com/item/1005004380577244.html
Not the fastest way (ordering from Aliexpress) to flesh out your mesh, but reports of their performance are great.
Edit: 
These ones:
You can see “last hop”, meaning the last repeater a device routes through before reaching the hub, by going to the webpage http://YourHubsIPAddress/hub/zigbee/getChildAndRouteInfo
well it appears that I do have things repeating....
Although it does not appear to be logically done. Cat food bin and dog food bin are both in the kitchen with the crockpot outlet yet they are apparently repeating tv lights which is in our bedroom upstairs.
I can’t remember the specifics of incost/outcost etc, but those numbers are pretty bad. I guess they are repeating because there are no good repeaters to use instead.
A way to see how your repeaters are doing:
The lqi is an indication of interference or quality of hop between device and nearest router.
The rssi is the signal strength. Closer to 0 the better as that means less power was used to transmit.
Usage is to track down a zigbee endpoint device that is dropping off due to interference or weak signal.
Or to find sources of interference or range or a sensor.
Keep in mind ZigBee does attempt to optimize itself automatically. So a single response isn't worth acting on, its the averages.
Moving a device might result in better signal, but it could optimize through a bad router and lqi could decrease in quality.
What this doesn't show is the hops between the nearest routers and the hub for each device. So its not the entire picture.
For most, its not even needed to look at or monitor. But it is handy for troubleshooting edge ZigBee devices that might be having issues on the mesh.
In almost every situation, adding repeaters / routers will solve the problem. It is a mesh after all.
So, if you have numbers of lasthopRSSI in the minus 80's, that indicates that you should move a repeater closer to that device.
Also, from another post: (kudos to @Tony ):
A few interesting things I've read about RSSI: as a 'raw' measure of signal strength at the Hub's Zigbee receiver during the interval in which it is listening for a message, it could also include noise or interference (in the frequency band of the assigned channel), "foreign" Zigbee transmitters using the same channel, as well as the paired transmitters in your Zigbee mesh. Values approaching zero indicate stronger signals, more negative values weaker (-100 would be the lowest reported value).
As it is the value of the 'last hop', if the device passes through a repeater it would represent the transmitted signal strength of the closest repeater's radio. For a small network with a few repeaters you may be able get an idea of how your end devices are routed (if their RSSI always tracks that of an individual repeater-- assuming the repeater's RSSIs are appreciably different).
so an lqi of 255 is good or bad?
Well my dbi may suck but at least lqi seems to always be good
Actually you can't really tell if a bidirectional link will function well based on one LQI figure alone, since it only tells you half the story... you need good reception at the near end (that's what LQI measures) along with good transmission (the remote side of the link needs to have good reception also).
Differences in antenna design/location and signal blockages and reflections mean that a good receiver doesn't always function as a good transmitter.
Luckily Zigbee repeaters swap status with each other periodically and take this into account when choosing routes; you get a better indication of reception/transmission on the path by looking at the reported in/out Cost figures; they're derived from the LQI measured at each end of the link.
Based on the outCost figures shown in the screenshot, two of the repeaters aren't useable for routing; the remaining three have good reception yet their transmissions are being indicated as weak at the remote end of the links. You might try relocating some of the repeaters; try one closer to the hub (even though that seems unnecessary) and see if the outCost figures improve (get lower, but non-zero).
Coincidentally this is being discussed in another thread: https://community.hubitat.com/t/help-with-zigbee-network-sengled-e1c-nb7/104176/42?u=tony
Thanks for your reply. I knew when looking at @markbellkosel84 ’s route table that it appeared he only had one viable router doing the lion’s share of the work, but couldn’t remember how the incost/outcost figured into how routes were chosen. Just that 1 was good and zero or 7 were bad.
@markbellkosel84, My hubs are dead center in our house (not in a closet), somewhat discreetly placed above a china cabinet. This wasn’t initially the least painful placement option as it required that I run ethernet cable across the crawl space and into the closet behind the aforementioned cabinet as well as wiring a new outlet, but this is what my route tables look like:
I have mine also central in the house. However, in my case I think the fact that I also have our main access point near by (also central) is an issue.
I have two hubs. One for the main work and the other for the LAN stuff (no radios) perhaps I need to move them to seperate areas of the house and reconfigure them to share radio duties.
As long as the RF space is deconflicted then you should be OK. I have HE on Zigbee channel 20, Philips Hue on Zigbee 25, then I have 5 Unifi APs scattered about on channels 1, 6, and 11. My Zigbee mesh is pretty solid.
Not a terrible idea. I have our main router about 10 feet from the hubs, but have read that keeping it a few feet away should be sufficient as long as you choose the right Zigbee channel. My 2 HE hubs are on channels 19 & 24 (mounted next to each other), while the Hue bridges are on 20 & 25, but located more central to the devices they control. The mesh routers choose their channels (which makes me a little crazy), but that hasn’t had any noticeable impact in my situation at least.
This work in progress shows where my central AP is (just above the cabinet) and the hub is temporarily just outside the cabinet on the lower left corner. Currently I have my numbers SLIGHTLY improved to the mid 70s.
I had mine in a closet briefly. It really effected signal strength, which is what prompted me to move it out. I drilled a hole in the wall and fished the ethernet cable through to the other side and mounted the hubs with velcro. I recently built in a china cabinet below the hubs which hides the hole for the cables that were previously hidden behind a large clock.
I think I might grab my 100 ft cat6 cable and do some testing when I get home. While it's centrally located right now it may not be the best thing being so close. I was previously holding tight to it's current location because of being central but I'm beginning to think that other factors are over riding that.
I assume with every move I need to shut down and disconnect power for 20 minutes to let the radio reset. I just hope this doesn't totally screw with Zwave.
Other thought I had was what about the external antenna mod that I had seen.
I think that just speeds things up as far as rerouting. Zigbee constantly monitors route signal strength/reliability and will self heal.
That depends on your soldering skills. I haven’t tried it myself, since I wouldn’t likely see any benefit in the risk/benefit analysis.
Yeah that is my hang up.....the soldering. I can but the high stakes of the situation.
Since you have two hubs, you could temporarily combine them and hit @lewis.heidrick up about getting the mod done on the spare.
Your ZigBee channel selection needs to change. Use only the the main frequencies between wifi 1,6,&11. 15, 20, 25 otherwise you're going to get blasted by wifi. Don't use 26 as it is an fcc power regulated frequency and operates at about half strength.
And yes, your signal strengths are really bad. You should consider either relocating the hub, get more repeaters, and/or antenna mod.
Download the Hubitat app
