not sure if you have it working yet - but if your using this setup:
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PC1
100Lan: IP 10.0.0.2, GateWay 10.0.0.1, SB Mask 255.255.255.0, DNS your provider's
1GbitLan: IP 10.0.1.2, Gateway 10.0.1.2, SB Mask 255.255.255.0, no dns needed
PC2
100Lan: IP 10.0.0.3, GateWay...