Hi @bastianhoss,
Unsure if you fixed this or not, but I ran into this issue yesterday so I'll post what I wound up doing for future searches...
if [client_address] =~ /^10\./ {
mutate { replace => { "[geoip][timezone]" => "Pacific/Auckland" } }
mutate { replace .....
} else {
geoip {
source => "client_address"
target => "geoip"
add_tag => [ "nginx-geoip" ]
}
}