Getting the error message like" Failed to establish a new connection" when I opened the outlook to browser 2

Hi,
I have tried below code and when I opened the outlook in browser 2 then getting the below error message. Please suggest me how to fix this issue?
Error message:

Code of the script:

*** Keywords ***
Login with approval account
${email}= open browser ${url} ${var}
switch browser 2
maximize browser window
run keyword and continue on failure Validate Credentials
run keyword and continue on failure Homepage should appear

Here is the code screen shot:

If anyone need more information, please let me know. it is big code so can not share all code. if want to show on call can share.

Please let me know how to solve this connection issue.