Default Can someone throw some light on this?

I have a weird Android app problem that I hope you may be able to shed some light on. I have the Securix app which is for monitoring my home CCTV system. I have an Xperia Z tablet and an Xperia Z1 phone. Both are on Android 4.3 firmware. The phone works perfectly with this app. However using the exact same settings on the tablet fails to connect when indoors on the local WiFi. It seems to work correctly when remote. (The Tab is WiFi only). Is there some networking difference between these devices that would cause this?