"Medium" doesn't really mean anything to us, as Medium is based on the wallet service you're using and how accurately it judges its fees to be based on the current network. Since you didn't provide any details of the wallet you used, I'm guessing you used a site service.
Time to move on to using your own wallet, so you can always determine the fees you need to get your tx confirmed within your required timeframe.
That said, your fee is above 251 sats/byte. I've been making just above that for the past 3 days and they all confirmed within 24 hours.
According to estimator
https://bitcoinfees.earn.com you need to wait just about that (90% chance of confirming under 20 hours).
Edit: just realised that tx has FOUR unconfirmed parents. And following them, more unconfirmed transactions. So... you're going to have to make sure all those confirm, from the earliest. Check out the sticky for more info on what else you can do... CPFP seems to be the best.