ok guys I got a fix for this.
The problem is that the galaxy tab is getting an IP address from your router and holding on to it. If a new device comes onto the network it will try to reassign you an IP but the galaxy tab will not allow, still wanting the old IP address.
The Fix is to create a static IP address. Go into wifi settings click menu and then advanced. Look up your dns server, gateway and netmask and set the corresponding fields in your galaxy tab settings. Make sure to also see what the IP range that your router can give (mine was 192.168.1.2 to 192.168.1.240)
Also dont forget to click use static IP address. I used 192.168.1.20 because I will never have 18 wifi devices on my network at once.
I hope this helps becuase I was banigng my head over the table for 3 days trying to fix this.
Oh and u have to turn static off when you use your wifi at another location