Ensure your router and Vodafone TV box are in the same room. Make sure your router has good line of sight and is not obstructed too much.
My experience with the extended routers was bad and I have now decided to move the router to where the tv box is. The Vodafone solution using extender routers was just illogical. They suggested to connect one extender router to the main router (???) and then the receiving extender router close to the TV box. I never understood the logic of an extender router connected to the main router. Just seems like an additional point of failure...
My next point is the lacking support and understanding of their own product. I tried to get troubleshooting support from Vodafone but literally nobody could provide an actual answer to my problem. Vodafone were reluctant to sort my problem out simply because they themselves did not understand how to solve the problem of router and Vodafone TV box in separate rooms. This is a simple case of a solution that was not properly tested and is fraught with problems.
If you have a faulty product you don't roll it out or suggest a setup that only works if router and TV box are co-located.
I do see potential for the product but Vodafone really needs to look at their processes to support their customer adequately.