How does Google search define a VPN?

Question

Google

Good afternoon. Faced such a problem -
https://gyazo.com/0488847453d81f56ff0c2c1af003caf1
There is a description on their website
https://support.google.com/websearch/answer/86640
1) This is my personal server.
2) There can be no automatic requests. Checked and sniffed all traffic.
3) Changed both ports and protocols, browsers. Openvpn TCP / UDP, Ikev
4) Blocking on subnets is also not suitable, because Neighboring IPs work fine.
Where to dig? Really tried everything. The methodology for determining that this is a VPN is absolutely not clear. Previously, I encountered this on mobile networks, but there because of the number of requests from one IP. I go to Google on holidays.
What could be?

Answer 1

>What can be?
Everything is very simple, you were given one of the subnets into which trash is pouring.
Send a request from whom you take ip / vps so that they deal with google and send a request to google. But there, in general, not everything is so simple.

Answer 2

It's not entirely clear what does OpenVPN have to do with it?
Google has never blocked and does not block connections through OpenVPN.