I tried playing with the CLI at work, where my Internet connection goes through a proxy. I can access 1password.com in a web browser, and I can "ping -n 5 1password.com" to see responses, but trying to use "op signin" with my family account and email address gives:
[LOG] 2018/09/14 15:27:08 (ERROR) Get https://EXAMPLE-FAM.1password.com/api/v2/auth/[email protected]/XX/HASHY/hashhashhash: dial tcp XX.XXX.XXX.XXX:443: i/o timeout
My web browser can access EXAMPLE-FAM.1password.com but pinging also fails.
1Password Version: CLI 0.5.3
Extension Version: Not Provided
OS Version: Windows 10
Sync Type: Not Provided