krackattacks-scripts | project contains scripts to test if clients or access points

There's no official support for testing devices in the 5 GHz band. If you nevertheless want to use the tool on 5 GHz channels, the network card being used must allow the injection of frames in the 5 GHz channel. Unfortunately, this is not always possible due to regulatory constraints. To see on which channels you can inject frames you can execute iw list and look under Frequencies for channels that are not marked as disabled, no IR, or radar detection. Note that these conditions may depend on your network card, the current configured country, and the AP you are connected to. For more information see, for example, the Arch Linux documentation. Note that the Linux kernel may not allow the injection of frames even though it is allowed to send normal frames. This is because in the function ieee80211_monitor_start_xmit the kernel refuses to inject frames when cfg80211_reg_can_beacon returns false. As a result, Linux may refuse to inject frames even though this is actually allowed. Making cfg80211_reg_can_beacon return true under the correct (or all) conditions prevents this bug. So you'll have to patch the Linux drivers so that cfg80211_reg_can_beacon always returns true, for instance, by manually patching the packport driver code.