Metrics shows UNDEF in total

[fedor-git]

Hello. I have trouble in stats:
when I try to get openvpn_server_connected_clients it shows data with UNDEF:
Here is Openvpn version 2 output:

CLIENT_LIST,UNDEF,XXX.XXX.XXX.XXX:60016,,,0,0,2021-08-05 21:30:28,1628188228,UNDEF,32,0,AES-128-CBC
CLIENT_LIST,UNDEF,XXX.XXX.XXX.XXX:52335,,,0,0,2021-08-05 21:30:26,1628188226,UNDEF,30,0,AES-128-CBC
CLIENT_LIST,UNDEF,XXX.XXX.XXX.XXX:45030,,,0,0,2021-08-05 21:30:47,1628188247,UNDEF,59,0,AES-128-CBC
CLIENT_LIST,UNDEF,XXX.XXX.XXX.XXX:54681,,,0,0,2021-08-05 21:31:18,1628188278,UNDEF,93,0,AES-128-CBC
CLIENT_LIST,UNDEF,XXX.XXX.XXX.XXX:48295,,,0,0,2021-08-05 21:31:14,1628188274,UNDEF,87,0,AES-128-CBC

Maybe I can filter with other variables but I think it's important.

[fedor-git]

I can count for example:
count(openvpn_server_client_received_bytes_total{common_name!="UNDEF"})by(instance)
I use it for many hosts and filtered by instance