My hotspot is on 5 GHz: why can’t some devices see it?

Connectify Hotspot uses the same Wi-Fi band and channel as your PC's own Wi-Fi connection. A Wi-Fi adapter can only be on one channel at a time, so if your PC is connected to a 5 GHz Wi-Fi network, your hotspot is on 5 GHz too. If your PC is connected to a 2.4 GHz network, you get a 2.4 GHz hotspot. This is the same whether Connectify Hotspot uses Wi-Fi Direct or Microsoft Hosted Network to create the hotspot. Either way it is a regular Wi-Fi hotspot, and your devices don't need to support Wi-Fi Direct to join it.

How to see which band your hotspot is on

While your Wi-Fi hotspot is sharing, look at the Connection details card on the Hotspot screen. The Wi-Fi channel row shows the channel and the band, for example 161 (5 GHz) or 11 (2.4 GHz). "Same as this PC’s Wi-Fi connection" under it means the hotspot is on the channel of the network your PC is connected to.

Connection details with the Wi-Fi channel row showing 161 (5 GHz), Same as this PC's Wi-Fi connection

If there is no Wi-Fi channel row, Windows didn't report the channel to Connectify Hotspot.

Why some devices can't see a 5 GHz hotspot

Some older devices only support 2.4 GHz Wi-Fi, for example the first Chromecast. If your hotspot is on 5 GHz, those devices won't show it in their list of networks and can't connect to it. Most modern devices support 5 GHz and will connect fine.

How to get a 2.4 GHz hotspot

Connectify Hotspot does not have a setting to switch between 2.4 GHz and 5 GHz. The channel of the hotspot is decided by the network your Wi-Fi adapter is connected to, and by the adapter itself. Switching between Wi-Fi Direct and Hosted Network doesn't change the band. These are the things that do:

Connect your PC to a 2.4 GHz network. Many routers broadcast a 2.4 GHz and a 5 GHz network, often with different names. Connect your PC's Wi-Fi to the 2.4 GHz one, then stop and start your hotspot.
Share a wired connection instead. If your PC can get its internet over Ethernet, choose that under Internet to share and disconnect your PC's Wi-Fi from the 5 GHz network (leave Wi-Fi turned on). Windows and your Wi-Fi adapter's driver then choose the channel. Check the Wi-Fi channel row to see which band they picked.
Check your adapter's band setting. Some Wi-Fi adapters have an option for the band they use. In Device Manager, open Network adapters, right-click your Wi-Fi adapter, choose Properties and open the Advanced tab. Look for a property such as "Preferred Band" or "Band". If your adapter has one, you can try allowing only 2.4 GHz. The names and choices depend on the adapter's driver.