Bastion Connection Error and How can I see the problems.

Hi. I am new in this Forum.

I would like to know how to fix my trouble I met these day.
Please help me.

1. I make some Win10 VMs.
2. I connected these VMs through a Bastion.
3. I met several connection errors to connect these.
   But, I could connect after some errors.
4. Some guys checked they can connect or not. They get connections successfully.
5. But, next day, two of five guys couldn't connect their VMs by Bastion connection errors.

I think I have connection to VMs successfully , so NSG's setting is not bad....
I have questions, how can know the situation?

I checked sessions from Bastion Page.
But it shows just "reading......."
Every time I checked the bastion, I just see "reading"
How can I check my sessions.....

Thank you very much in advance.

Toshi