I'm using a personal VPN on android 8.1 and trying to figure out whether all of my traffic is actually going through it or not. Despite always having the VPN on, the mobile data usage report shows data as being used mostly by the apps I'm using, and then slightly by the OpenVPN app.
For example I'll check my data usage, load a youtube video, and my data usage report will show youtube usage as having gone up 10MB, while the OpenVPN data usage went up 1MB. But if I look in the OpenVPN connection statistics, it shows that all 11MB went through the VPN, and if I check a site like ipleak.net, it suggests that at least my browser traffic is all going through the VPN. So does the phone just register data usage pre-VPN, and if so, how accurate is it considering the VPN tunnel can use compression?
Secondary question, for anyone familiar with Project Fi: How does their open-wifi VPN interact with a personal VPN? I haven't noticed my VPN switching over to theirs when it connects to a random open network, but I emailed their support and they said anything public would go through their VPN and anything on my private network would go through mine, but my OpenVPN statistics are still indicating everything is going through it.