my kids were killing my bandwidth, so setup separate guest wifi for them and only gave them 20 Mbs of my VM speeds (I am on 60 Mbs)
The document is for DDWRT router but also can be adapted to a Tomato firmware
Please note the document is based on a router that is setup a secondary WiFi AP on your network, but could be adapted to also be configured on your primary wifi router - not tested but you will need to modify the firewall rules and changed the variable lan_ipaddr to wan_ipaddr and lan_netmask to wan_netmask
The document is for DDWRT router but also can be adapted to a Tomato firmware
Please note the document is based on a router that is setup a secondary WiFi AP on your network, but could be adapted to also be configured on your primary wifi router - not tested but you will need to modify the firewall rules and changed the variable lan_ipaddr to wan_ipaddr and lan_netmask to wan_netmask