I have also found a Reddit thread related to the topic (https://www.reddit.com/r/Malwarebytes/comments/1dzj7vk/google_chrome_malware/?rdt=41068), as well as this thread on this forum (https://forums.malwarebytes.com/topic/313168-your-software-blocks-our-vpn-server-addresses/ ), that shows the same IP address as the one that shows in the prompt. As far as I am told, it may be related to AdGuardVPN, and I did have a Chrome extension. I removed it, and the pop-ups seems to have stopped. This information may be useful, so I think it belongs here as well.