I was hoping someone else would respond, because I am not that confident in what I have to say...
Are you sure it is a DNS issue? From your description, it is not clear to me that some network issue or something else might be contributing.
Suggest to change this:
dns-search farmhome.local www.farmhome.local
dns-nameservers 192.168.3.155 184.108.40.206
Do your windows computers get their network stuff via DHCP? and from where? (you mentioned not from your dnsmasq on your server) When you have the problem, perhaps look at the output from (on the windows computer):and compare with when it is working properly.