Connection issue in Itversity lab

Today I am using lab and I am using the web version. I am losing connections every now and then. Most of the times I am getting below error. Please look into this and let me know if I have to do something different to get rid of this situation.

400 Bad Request

The plain HTTP request was sent to HTTPS portnginx/1.12.2

Note : I cannot use terminal/Cigwin as I am not allowed to download them

Please send a mail to with the screen shot of the error. So that we can help you in a better way.