MikroTik RouterOS WAN Failover

#-------------------------------------------------------------------------------
# MikroTik RouterOS WAN Failover
#-------------------------------------------------------------------------------

#-------------------------------------------------------------------------------
# Settings
#-------------------------------------------------------------------------------
:local PRIMARYROUTELABEL "PRIMARY_ROUTE";
:local BACKUPROUTELABEL "BACKUP_ROUTE";
# Hosts to ping via primary route (Yandex.DNS)
:local PRIMARYHOSTS {77.88.8.8; 77.88.8.7};
# Hosts to ping via backup route (Yandex.DNS)
:local BACKUPHOSTS {77.88.8.1; 77.88.8.3};
:local PINGCOUNT 3;
:local PINGTRESHOLD 70;

#-------------------------------------------------------------------------------
# Check primary route
#-------------------------------------------------------------------------------
:local primaryOk false;
:local primarySuccessPingCount 0;
:foreach host in=$PRIMARYHOSTS do={
    :local n [/ping $host count=$PINGCOUNT];
    :set primarySuccessPingCount ($primarySuccessPingCount + $n);
}
:set primaryOk (($primarySuccessPingCount * 100) >= ([:len $PRIMARYHOSTS] * $PINGCOUNT * $PINGTRESHOLD));
:if (!$primaryOk) do={
    :log error "Primary internet connection down"
};

#-------------------------------------------------------------------------------
# Check backup route
#-------------------------------------------------------------------------------
:local backupOk false;
:local backupSuccessPingCount 0;
:foreach host in=$BACKUPHOSTS do={
    :local n [/ping $host count=$PINGCOUNT];
    :set backupSuccessPingCount ($backupSuccessPingCount + $n);
};
:set backupOk (($backupSuccessPingCount * 100) >= ([:len $BACKUPHOSTS] * $PINGCOUNT * $PINGTRESHOLD));
:if (!$backupOk) do={
    :log error "Backup internet connection down"
};

#-------------------------------------------------------------------------------
# Failover
#-------------------------------------------------------------------------------
:local primaryDistance [/ip route get [find comment=$PRIMARYROUTELABEL] distance];
:local backupDistance [/ip route get [find comment=$BACKUPROUTELABEL] distance];
:if ($primaryOk && ($primaryDistance >= $backupDistance)) do={
# Switch to primary route
    /ip route set [find comment=$PRIMARYROUTELABEL] distance=1
    /ip route set [find comment=$BACKUPROUTELABEL] distance=2
    /log warning "Switched to primary internet connection"
# Remove all connections
    /ip firewall connection tracking set enabled=no
    :delay 5s
    /ip firewall connection tracking set enabled=yes
};
:if (!$primaryOk && $backupOk && ($primaryDistance <= $backupDistance)) do={
# Switch to backup route
    /ip route set [find comment=$PRIMARYROUTELABEL] distance=2
    /ip route set [find comment=$BACKUPROUTELABEL] distance=1
    /log error "Switched to backup internet connection"
# Remove all connections
    /ip firewall connection tracking set enabled=no
    :delay 5s
    /ip firewall connection tracking set enabled=yes
};