Assigning one port out of NAT

RouterOS Beginner Basics
1

Hello, I have RB750Gr2, using NAT and I need to connect my ISP’s set top box without the router, IGMP does not help with multicast as the device probably uses different VLAN in the ISP’s network. The STB has a 4 port gigabit switch/something built in so the wan cable should be connected to its wan port and then the router can be connected to lan port. This way it’s possible to pick up the multicast stream on the STB as well as have the same internet access with the router.

However my cabling in home does not allow me to run wan cable to my tv so another working option is connecting the STB, router’s wan port and ISP’s wan cable to a switch. I’d prefer not to buy another device if possible and I was wondering if the same can be achieved with the router already.

Simply, I’d like to make a “switch” with one of the router’s lan ports and the wan port and connect the STB to this lan port, so it would be like the router is not even there. NAT will have to work for the rest of the ports where computers are connected.

Example: wan, lan 1-4
lan 1-3 would be behind NAT, lan 4 would have direct connection to wan. The router will pick up an IP address from the ISP on the wan port, the device on lan 4 will pick up its own IP address directly from the ISP and would be fully reachable from outside.

Is this even possible? If there’s a solution, can you please let me know how to set this using webfig?

Thank you very much.

2

I dont know what configuration is using your isp but you can create a bridge, lets say bridge-isp with two ports, , let`s say ether 2 and ether 3 added to the bridge interface. Port 2 will be isp cable and port 3 will be STB wan cable . Then ether 1 set as wan connected to lan port of STB and ether 4,5 bridged in another bridge , bridge-lan to your network.

3

I don’t want to run any other cable from my STB back to router.

Would it be possible if I make a bridge with router wan+ether1, connect isp to wan, connect stb to ether1, and computers to ether2-4? Will I be able to run NAT on the bridge, but the NAT would not affect the STB?

Thanks

4

I doubt it will work. but you can try this : like you said… ether1 with isp ether2 to stb , ether1,2 in bridge-isp, then depend how you connect add a dhcp client or pppoe connection to bridge isp. Again, i doubt it will work becouse i think your isp use tagged vlans. If not working like this you will need that cable from stb back to router.