Session freezes after a while. Normally a reboot of local computer solved the problem.

We are sorry you are running into issues. To discuss issues we recommend to share your problem on our Tech Community forum (https://aka.ms/wvdtc) or open a support ticket after you have reviewed the troubleshooting options in our documentation (Windows Virtual Desktop troubleshooting overview - Azure | Microsoft Docs)

We recommend to review our troubleshooting section first. The other option you have is to open a support ticket through the Azure Portal.