I'm not sure what can be the reason why your tablet keeps changing its IP address but you could try to fix it by assiging a static IP.
I'ts just a quick fix.
On an Android tablet, go to Settings > WiFi, tap and hold the active network, then tap 'Manage network settings'. Tap 'Show advanced options' and scroll down to IP settings, then change 'DHCP' to 'Static'. Tap 'Save'.