Upvote:1
Based upon the formulae in your refusal notice, this is a captious refusal. They are rarely issued.
What this generally means is that they found something objectionable (or several things), but there was no refusal formulae they could use (either for security reasons or for reasons related to your personal circumstances).
It could also be that something flagged up on your hosts, but that's less likely. Have your hosts sponsored previously? Do you know your hosts solely through the net? Do they have a clean record? Stuff like that.
Whatever it is, you'll need to fix it before applying again. The fastest way is to instruct a fee earning member of the Law Society to represent your next application. You'll need to provide them with copies of EVERYTHING you submitted (I'm guessing the cost will be about GBP 900+, more for the very best, but it's a guess only). Nobody will be able to give a precise estimate without assessing the complexity of your case, and that means getting all your stuff spread out on a table and looking at it carefully.
Secondarily, you can spend a few years getting lots of peripatetic experience in places like the USA, Canada, or Schengen zone. It takes a lot longer, but they love to see that kind of thing and it almost always guarantees success.
It wouldn't be advisable to make a fresh application right away because if you send the same stuff or even change it, they will refuse again. And if your new stuff contradicts your old stuff (even a little itty-bitty bit), matters will be worse.