Hey! I've got a few tips for you. First, ensure you have the latest app version and your phone's software is up to date. Sometimes, that can solve the problem. Also, check the app settings to see if there's an option to enable the guest feature.
If that doesn't work, try restarting your phone and the DS HD1 device. If it persists, try another app for videoconference, like UCaaS Provider. I hope that helps!