I have been having this problem ever since our box software was "upgraded" to TV360 last August. I'm in the same situation as you, it's just not practical to connect my TV via ethernet cable to my Virgin router as it's on the opposite side of the room from the Hub 3. Our coax cable actually goes under the floorboards as we have a crawl space.
I'd just like to compare notes with you. The problem happens when I go into Home to use an app or watch a recording and get the purple screen just with headings and no pictures. Eventually the "Oops" message appears. Sometimes it happens when I've been watching a recording and when I come out of that I have the same issue. Yesterday I had to reset the TV box at around 3.30pm and again at around 9.30pm (pull the power cable, wait for 30 seconds, blah blah). Like you I'm having to do this at least once, if not twice or more times, each day.
I sometimes get the black dialogue box with varying error codes. Yesterday afternoon it was CS9994. It said that the Hub had disconnected, but I had two phones, an iPad, a desktop and a laptop that were all quite happily working away on the same WiFi connection. So I didn't reboot the hub, just pulled the plug on the TV box and it came back.
Last night's problem was a first. I went in to watch a recording, but instead of a purple screen I had a black screen with only the word "Home" visible. The remote control was unresponsive, except when I pressed the back button and was faced with a completely black screen. Yup, you guessed it, power cable pulled out and everything worked perfectly fine again.
I will try the suggestion to switch from 5 to 2.4 Ghz connection. Have you done that yet and has it made any difference?