High Droprate in OpenVPN

[c-mu]

Hey Guys,
since longer time, i'm monitoring high drop rates at my vpn connections. now i want to go for it and find out the reason why this happens. But i don't have any clue where to start.

see the attachment as example. Thats the output of the prometheus exporter regarding some interfaces. As I can see, the problem in only located at the vpn connections. WAN/LAN etc does not drop (or errors) ANY.

Any Ideas what that could be? All VPN Connections are from Type OpenVPN and TCP. I have some IPSec Tunnels too, but the prometheus exporter doesn't fetch them, so I cant say if that is only a OpenVPN Problem.

Thank you for any advice!