Are you using a cable modem, without a router? It seems that cable ISPs use a private LAN configuration to manage their networks, and provide DHCP addresses. Then they tunnel your connection thru their network, and out to the Internet.
Having svchost.exe set for outgoing only is the right setting to use.
If this is probably your ISP networking traffic and you are logging the blocked packets, then your log should show are very large amount of traffic on UDP ports 67 and 68. These are the DHCP ports. If you are seeing only a few 10.x.x.x IP addresses to these ports, then you’re seeing your ISP do it’s work. That means the traffic you’re seeing is harmless to you, in which case you can block it and forget it.