Pfsense on Proxmox with KVM on an Hetzner Server

[Selters]

Hello
I has try to get Pfsense working on my Hetzner Server with KVM Virtualization in Proxmox.

I have 4 IPś,  and use 1 for the WAN on Vmbr0 , and as Gateway the MainIP from Server.
But the Gateway Monitor is only short Online and than Offline.
The same setup works with Endian and astaro out of the box.
My Proxmox Network Settings:

# network interface settings
auto lo
[code]iface lo inet loopback

auto eth0
iface eth0 inet static
        address  176.9.17.15
        netmask  255.255.255.224
        gateway  176.9.17.1
        broadcast  176.9.17.31
        pointopoint  176.9.17.1
        post-up mii-tool -F 100baseTx-FD eth0
        post-up echo 1 > /proc/sys/net/ipv6/conf/eth0/proxy_ndp
        post-up echo 1 > /proc/sys/net/ipv4/conf/eth0/proxy_arp
        post-up echo 1 > /proc/sys/net/ipv4/ip_forward[/code]

auto vmbr0
iface vmbr0 inet static
        address  176.9.17.15
        netmask  255.255.255.224
        broadcast  176.9.17.31
        bridge_ports none
        bridge_stp off
        bridge_fd 0
        up ip route add 176.9.33.12 dev vmbr0
        up ip route add 176.9.33.14 dev vmbr0
        up ip route add 176.9.27.26 dev vmbr0

auto vmbr1
iface vmbr1 inet manual
        bridge_ports none
        bridge_stp off
        bridge_fd 0

auto vmbr2
iface vmbr2 inet manual
        bridge_ports none
        bridge_stp off
        bridge_fd 0

I has try to spoof the MAC from Host eth0 but not working , than i has try to use an sepearte mac but thats not works.

Setup:
WAN IP:176.9.33.12
Gateway:176.9.17.15 Gateway monitor only some seconds Online than Offline.

Must i add an Firewall Rule or make an Routing or so?
thanks