diff --git src/PVE/INotifyEtcnetOverride.pm src/PVE/INotifyEtcnetOverride.pm
index 2a61264..f5a8a9b 100644
--- src/PVE/INotifyEtcnetOverride.pm
+++ src/PVE/INotifyEtcnetOverride.pm
@@ -658,7 +658,7 @@ sub __read_ipv4address_into {
        chomp ($line);
        if ($line =~ m!^\s*(?:$|#)!) {
            # skip
-       } elsif ($line =~ s!\s*([\d\.]+)/(\d+)\s*!!) {
+       } elsif ($line =~ s!\s*([\d\.]+)/([\d\.]+)\s*!!) {
            $f->{address} = $1;
            $f->{netmask} = __unwrap_netmask4($2);
            __line_broadcast_into($path, $line, $f, 'broadcast');
@@ -686,6 +686,7 @@ my %nm4prefix = qw/
 sub __unwrap_netmask4 {
     my $in=shift;
     my @out;
+    return $in if ($in =~ /\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}/);
     while (@out<4) {
        if ($in>8) {
            push @out, '255';