This is a possibility on any network though. I have had multiple instances of a single device killing a wired Ethernet cable. I have had one wifi device kill my Zigbee network years ago. I have also intentionally configured a Zwave power monitoring device poorly and killed Zwave. My point is it is possible in allot of ways to bring down a entire network with one device. Most of those examples involve the misbehaving device spaming out traffic and overloading devices.
LR will just move the impact from potentially the mesh network to the hub. I would expect LR devices to still be impacted on occasions where a hub is generating a Zwave network is busy messages in logging.
@sean5
Unfortunately removing ghosts can be a little bit of a exercise in patients if you have any.
I don't have a C5, but a C7. I think it is similar but I may be wrong.
The first thing to do is open up your "Zwave Detail" page from the hubs "Settings" menu. On that page, look for devices that don't have a name, don't have routes or a last time for talking to the device. You can take a screenshot of that page and put it here for review. Some devices won't have routes or a last message data/time if the hub was recently restarted. You can also obviously have ghosts if there are more devices listed on that page then you have.
Once identified that way you should click on Refresh next to let the hub try to connect to it and validate the connectivity. Once that fails click on the remove button that appears. Sometimes it takes more then one time to get a device removed. Sometimes you will need to reboot and remove power from the radio and try again as well. If that doesn't work the last option is to use a Zwave USB stick connected to a computer with Zwave controller software to for remove the ghosts. There are directions out there for this.
Another option that comes to mind you may want to consider. Since option you don't want to buy more because of current reliability, first try to simply move the switch closer and see if it becomes more reliable. If it does become more reliable then you know it was the range and not the switch itself. Then you can add a new switch back to that location to see if it works better.
You will see a lot of benefits from the C8 Hub actually. Going from the C5 to the C8 you will get Zigbee 3.0 and go from Zwave 500 to a Zwave 800 Radio with the ability to support Matter and Zwave Long Range. You also get USB-C power port instead of the fragile Micro USB port, The ability to connect with Wifi was added with the C8 as well.
If you go to the C8 Pro you also get 2GB of ram instead of 1 GB with the previous hubs and a faster processor with many SOC improvements. The one mainly discussed is the new CPU is anywhere from 20% to double the current speed of the older models. but the new SOC has allot of improvements under the hood as well.
