Eliminate daisy chaining switches

I have Sophos UTM 9.4 setup to run on a virtual machine and it's working ok.

My issue is I have a couple switches daisy chained and I think it's making my internet connection a little flaky.

I have:

AMD FX6350
8G Ram
500GHD
RealTech gigabit NIC onboard <eth0>

RealTech gigabit NIC card        <eth1>
Intel gigabit NIC(s)                     <eth2>, <eth3>

Ubuntu 14.04 OS

VirtualBox V4
Sophos v9.4

I have <eth0> bridged  internal management port

            <eth1> external Internet
            <eth1>, <eth2> and <eth3> NAT

RIght now all internal is routed through <eth0> with two 8 port switches daisy chained, which works, mostly.  My wife's iPad regularly looses internet service while connected to my Netgear WNDR3400 wireless router.

The wireless router is setup as an access point but not DHCP.  All subscribers are routed to <eth0> over one of the internal ports (not wan) where Sophos assigns IP addresses..

What I want to do is run my wireless through one of my extra NIC(s) to eliminate one of the daisy chained switches.  I know a little about networking and IP masking but not enough to make it practical. 

Can someone tell me how to setup Sophos for more than one subnet so I can utilize my two extra and unused NIC(s)? ( If that's what I need to do)

Charles