After 7.1->8.0 VPN S-to-S routing doesnt work anymore

[Sycoriorz]

After Upgrade from Zentyal the routing goes partly lost. It is an Site-to-Site Zentyal to Zentyal Vpn Network which is affected. Rest of VPN servers which is for normal road warriors runs like expected.

Following route gets lost. On my Zentyal 7 Server the route is exactly like that.

Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
10.20.1.0 10.10.5.9 255.255.255.0 UG 20 0 0 tap1

After adding this route over ''ip route add'' it works like expected.
But it isnt persistent

Expected behavior
persistent route which look like above.

Where i need to add this route that zentyal doesnt overwrite it and it is include in backup with full support.

many thanks