I have two physical networks; one for data and one for my surveillance cameras,  Currently, the cameras are not available on the Internet.

In my home server, I have two NICs, one connects to each network and I can see both networks just fine.  On my Synology Disk Station, I have two NICs and it is connected to both networks as well.  The Synology serves as DHCP server for the video network.  Everything else connects to just the appropriate network - PCs, laptops, tablets, phones, etc. on the data network while multiple video recorders, video monitor workstation, and cameras, connect to the video network.

The data network connects through a TP-Link TL841N to my fiber-to-the-home network.  The TL841N serves as DHCP Server for the data network.

Now that I have unlimited Internet plans on my phones, I want to be able to view my cameras on the Internet.  I currently monitor and record to the Internet through the Synology but I don't get all the alerts and functionality the Hikvision apps would give me if I could get to the cameras directly from the Hikvision apps.

My plan is to simply connect a second TL841N WAN port to a LAN port on the data network TL841N and set the LAN side of the second 841 to the video network address block and add a bunch of port forwarding.

Seems simple enough but as soon as I connect the second router, I can no longer access the video network from either multi-homed device: the Synology Diskstation or my home server. 

So I have basically 3 things I'd like to find out:

1. Is this the right basic approach?
2. How can I solve the problem of the multi-homed devices no longer being able to communicate with the video network?
3. Or, as a last resort since it defeats the whole purpose of splitting the video off the data network, how can I create a manual route that would let me see the video network from the multi-homed devices?  I tried to do it but either did it wrong or it just isn't going to work.

Thanks,

Dale