It is not a violation to be logged in on your account from multiple devices. If any inconstancies are noticed our team will reach out to you directly with more information. Thank you.
You are allowed to log into your account via different IP addresses/computers as long as you don't share your account with another person. It's important that you don't share your log in credentials with anybody and don't log into other users' accounts as it's a serious violation of Upwork TOS.