its coax but not just any old coax - its tripple shielded or gold plated or whatever - its said to be special to VM so you should not add to it - plus adding 3 metres could have an effect ob the input to the hub
in short you need a tech to do it and that will cost you £99 as a non fault call out which they will not do until covid lockdown is over
so alternatives
1 - its worth giving them a ring start with UK retentions
dial 150 or 0345 454 1111 and follow the prompts to - 'thinking of leaving us' - dont worry about that they do much more - open 8am -10pm 7 days a week - should take you to a UK call centre
ask nicely they do do a 3metre cable that comes with the TV box - someone might be able to send you one - if you are out of contract you could twist an arm by mentioning 30 days notice even if you are not serios
2 - assuming you get nowhere with one and dont want to pay £99 for a cable - leave the hub where it is - put it in modem mode and buy a 3rd party router - better value for your £99 and put the new router where you want it - connect it back to the hub with a lan cable - sorted
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Tony