I wanted to chime in here with a discovery I made this past weekend. Long story short I migrated a C7 with the antenna mod to a C8 Pro earlier this year. On the C7 I was using the L-com 5 DB Rubber Duck antenna that was recommended in the mod post. When I setup the C8 Pro I used this same antenna because of how I have my hub mounted on the wall, I wanted the antennas straight up vs on the side. The stock antennas don't bend.
All was well with the zwave migration: all devices worked well and things were snappy. A month or so later, I went to replace a bum Jasco switch and I couldn't get new devices to pair on the new C8 Pro. I reached out to support and they couldn't find anything wrong either. I ended up booting up my old C7 and replaced the switch and did the cloud migration again and didn't think anything of it until this past weekend.
This past weekend I needed to remove several zwave devices and replace yet another 2017 era Jasco switch and again nothing new would pair. Zniffer showed no NWI packets coming from my C8 Pro zwave radio. I moved the hub upstairs closer to my PC running the Zniffer software but this time I used the small antennas that came with the hub and boom device paired! For giggles I grabbed the L-com antenna from downstairs and nothing would pair and Zniffer again showed no NWI packets.
So for some strange reason this L-com antenna worked great on my C7, worked well with migrated devices on my C8 Pro, but wouldn't allow anything new to be paired.
I wanted to post this here in case anyone else is using these antennas on their C8 and you are having issues.
