hmmm, that post makes some of the previous posts bit vague
how exactly is your setup?
ie:
PC1 > N300
PC2 > N300
Modem > N300
??
From N300 modem/router 1st ethernet port to PC1 on-board NIC via short cat6 cable.
From N300 modem/router 2nd ethernet port to PC2 on-board NIC via 10M cat6 cable.