I found one relevant thread with the exact same modem on another forum I am on - http://forums.whirlpool.net.au/archive/1510617
Advice then was
On the left hand menu.. click Thomson Gateway.. Configuration..
On the screen that opens, click on the Configure on the far right near the top.. this is important to understand how the gui works.. there are multiple screens and you need to get familiar with this.
Web Browsing Interception: Select disabled.
Edit - seems to be a re-occurring thing with this model - http://forums.whirlpool.net.au/archive/1548175
and same udp flood again - http://forums.whirlpool.net.au/archive/1596763
It is also referenced as DoS - Denial of Service settings
Edit - you may need to do the below in the spoiler