We are about to start deploying 834v6 gateways and have discovered an issue with communicating with a Dell Inspiron 7548 laptop that uses an Intel Dual-Bank Wireless-AC 3160 adapter. For some reason, this laptop will not see the advertised SSID coming from the 834v6 (tried on multiple units) whether the SSIDs are grouped or separated into 2.4 and 5 GHz. This laptop has no issues with seeing and connecting to any other SSID broadcast by other APs. I've verified that the driver for the wireless adapter is the most current, as is the firmware for the 834v6.
Have you tried a different channel? Maybe try 1, 6, or 11. Sounds like it's both 2.4GHz and 5GHz?
I've not tried different channels, but I will. The strange part is that it isn't showing up on either 2.4 or 5 GHz. This is a 5 year old laptop, but I've tested with a 15 year old desktop (2.4 only) that works fine.