Welcome to Vodafone Community
I have been using the Gigacube for several moths now although recently the Wifi speeds on other devices such as my phone and tablet have been really slow. I also have a wired ethernet connection to my PC which gets high download speeds on Steam/Youtube, but basic browsing is very slow and in most cases unresponsive.
I have contacted Vodafone, although their only advice was to reset the gigacube, remove the sim card and wait 30 seconds and try a different location in my house.
Any other troubleshooting tips to rectify this?