What fiber optic network interface card do I need for a WAN connection

Solution 1:

You don't want to buy a "fiber card". What you want is a card (or preferably a switch) that has either SFP or SFP+ ports.

This will allow you to purchase cheap optics depending on what you need, and will ensure that you're future-proof if you need to upgrade or change optics in the future.

As for what type of optics you'll need, that's a conversation you will need to have with your ISP. Whatever you have will need to match whatever is on the other end of your fiber pair.

Solution 2:

You need to find out what standard your ISP is using before you can start shopping for hardware to connect to it.

IF it's a fiber ethernet variant then you can use a network card with a SFP/SFP+ slot (SFP is for 1 gigabit, SFP+ for 10 gigabit) and a suitable transciever module.

If it's GPON then internal interface cards for PCs don't seem to exist, it seems you have to buy a seperate "GPON modem".

If it is some legacy telco standard you will need different hardware again.