Epic have spent about a month investigating this and confirmed that from their point of view it should be working and have pointed me at the ISP (BT) to resolve or enable the social media category. I don't really want to do that that last one, I'd much rather have control of which social media sites my children can access due to the associated dangers and have a solution to enable the voice chat. At the moment, I have to re-enable it temporarily when players want to chat, the disable it again afterwards which is not really practical. I also don't know how to contact BT directly on this issue.
Does anybody have any suggestions on either a solution or how to contact BT on this?