Hi, @HappyHarry
Thanks for posting, and welcome to the Roku Community.
We came across your post where you have an issue connecting your Roku Express 4K+ to the 5GHz network, and we'd be happy to assist. There are a few reasons why Roku devices cannot connect or detect the 5GHz network. First, we recommend performing a system restart on your Roku device by navigating to Settings > System > Power > System Restart.
If the issue still persists, we suggest getting in contact with your Internet service provider since there is a need to change your network settings to make the 5GHz available and compatible with your Roku device.
Let us know what you find out.
Best wishes,
Kash
Takashi O.
Roku Community Moderator