Well, the SB8200 is a modem only device and not a router. 

What router did you connect it to?

my bad. I meant that I connected to the modem. not the router

Don’t connect it directly to the modem. 

Reason why is the SB8200 might have 2x ethernet ports but the vast majority of ISP’s only all 1 public ip address. meaning only 1 device can be connected to it. 

Go modem--->router---->nas

Interesting. I have the computer connected to a dlink switch on my desktop and that goes to the modem. I have the Synology plugged into the same switch. the computer can connect to the internet, but the sinology cant. I also tried to connect the Synology directly to the modem with no luck.

It won’t work. The SB8200 ISN’T a router. And, again, most isp’s only support 1 public ip address. 

So if the computer works, nothing else will. You need a router to connect to the sb8200  so it can assign private ip addresses. I’d also recommend having a router just for the built in firewall they have. Having your devices directly connected to a modem is a recipe to get your info stole/stuff hacked. 

Cool thanks. I will get a router to connect and see if that works. 

Thanks

If I got a router and plugged that into my dlink switch would that work?

nope. You’d need to go modem--->router--->switch/devices.

You didn’t put what switch you have but most people have unmanaged switches. They don’t have routing capability. They’re simple unmanaged switches. 

You need something to handle dhcp/nat like a router. 

That’s what assigns the private ip addresses 

I do have. a netgear, wireless router in the system for wifi. Could I go modem>netlink>switch? I am not sure it is setup like that now.

yes it is a dgs 105 unmanaged switch

Thanks for your help. I bought a router off Amazon hooked it up reset everything  and I’m good to go. My lack of knowledge is what led to my frustration! Again thanks so much. There are lessons to be learned in everything we do!