ISR 4331 mention that it has "3 - Total onboard WAN or LAN 10/100/1000 ports" and same it says "2 - RJ-45-based ports".
So if I need to have 3x1GE ports can we select ISR 4331 instead of 4351. My requirement is 3x1GE and 2xSFP
Actually my customer need 3 WAN ports. So i assume we need to go for NIC card ryt
Without knowing what the (total) WAN speed I cannot make any comment nor recommendation.