Forwarding broadcast/multicast packets trough pptpd

Hardware Hub Networking
1

so, not sure to post this in networking or in linux, let me know if its in the right/wrong place.

i have pptpd on an ubuntu server on my home network, and (aside from some odd cases) i can connect to it flawlessly, and send packets both from the pptpd-connected laptop to my home network, and from my desktop to the pptpd-connected laptop.

one thing that i cant wrap my head around how to do is have the linux box forward broadcast/unicast packages to and from the vpn connection.

i'm not very skilled with iptables commands on linux, and most of what's working now is a matter of "did this work? no - try something else, yes - good"

the network setup is as following:

-wireless modem (what i'm connected to to test)

--router

---desktop

---server

where the network behind the router is "192.168.1.0" with dhcp set to give ip addresses 10-50

100-199 is for static ip addresses

200-230 is for testing purposes

231-240 is the range the pptpd clients get put into.

 

my end goal is to have windows home group work over the vpn connection, as well as steam "in-home" streaming.

2

Just looking online people have setup pptp on the windows machine hosting the steam stream and this works. 
Its probably a iptables rule then limiting on the ubuntu box. Have you tried stopping ip tables and seeing if that resolves it? before you go looking into rule changes?  
as root(sudo) just stop the service "service iptables stop" if using ipv6 you can stop that with ip6tables. 

3

there doesnt seem to be an iptables service, and as far as i know i need the actual iptables to get the traffic to flow trough my server between laptop and desktop. or am i wrong here?

EDIT: you also seem of the idea i'm doing the steam thing between the pptp client and host, the thing i'm doing is that the pptp host is a machine on the network, thats supposed to forward the steam traffic to other devices on the network.