Here's some info from https://community.bt.com/t5/YouView-Box ... -p/1137730
Although it's for a different set top box the principal is the same with other services.
I've used it successfully myself to connect IPTV STB's to ISP's Multicast services.
Additional info here: https://wiki.mikrotik.com/index.php?tit ... edirect=no
I'm using a 750G, this should hopefully work for at least any device running RouterOS 6.x, I have the Openreach Huawei Infinity modem connected with cat5e to eth1 on the Mikrotik and the internet connection is then dialled with PPPoE over eth1.
Give your VouView box a static IP or reserve its DHCP address. I've isolated my YouView box, directly cabled it to the router's eth5 (I've removed switch group config) and put it on a different subnet etc, I don't think this step is necessary though so I won't go into detail. I felt better about my LAN security doing it though.
Go to the Mikrotik download page and get the all packages zip for your router, extract and install the multicast npk by dropping it into Files through Winbox and then restart the router. You should now find "IGMP Proxy" in the Routing section of Winbox, open that.
The IGMP traffic won't appear to come through the PPPoE interface instead it will be on the ethernet interface that is physically connected to the Openreach modem, in my case eth1. You'll need to assign an IP adress to this interface if you haven't already, making it anything in a private range but outside your LAN ranges, e.g. 10.20.30.1/24, only because RouterOS won't make use of the interface without an address assigned.
Add an interface in the IGMP-Proxy, select the interface the modem is on from the drop-down, in additional subnets enter 0.0.0.0/0 and finally tick the upstream option and save it. Then add another interface and select whatever interface your YouView is reachable on from the drop down, don't change any other settings and save it.
Enable Quick Leave in the settings of IGMP-Proxy, this allows IGMP devices to send a leave notice and stop a stream instantly so you don't get flooded with UDP traffic until group membership times out.
IGMP-Proxy allows devices on the LAN to send an IGMP membership request, it will be picked up by the router and forwarded on the configured upstream interface, IGMP messages to the group address will then be forwarded back to the device by the router according to the entries auto-generated in the MFC tab.
Your router needs to actually accept the IGMP traffic on the selected interfaces, it will be seen as addressed to the router so add a rule to the input chain in IP > Firewall > Filter Rules, enter igmp as the protocol, action as accept.
Then add a rule to both the input and forward chains, dst address is the multicast group that will receive the IPTV streams, protocol is UDP, in-interface is the upstream in IGMP-Proxy, action is accept.
You can discover the address of the multicast group from the MFC tab in IGMP-Proxy (an entry should appear if you attempt to tune an IPTV channel, 900 is good to test) or by adding a rule early in your forward or input chains with dst-address as 188.8.131.52/4, protocol UDP, in-interface as the upstream in IGMP-Proxy and action as add-dst-to-list with whatever list name you choose. I found all channels I tried to be in 184.108.40.206/24, I don't know if this differs or is the same for every BT customer.
Now go to your YouView box and tune to 900, if you've got the multicast group right it should work, picture should appear almost instantly and you should be able to see the traffic moving through the router.