Hi WinturMjoet,
You might try contacting the Montenegro national tourism office -- they should know.
But your safest bet may be to take Croatian ferry operator Jadrolinija’s ship “Marko Polo” from Dubrovnik to Bari. Dubrovnik is a fairly short bus ride from Montenegro.
I’ve taken the ferry between Bari and Bar several times in past years, but this year the situation is VERY confusing to me. (I’m in the USA, so not close to the situation).
For the past few years, the route was being operated by Jadrolinija, with their (very nice) ferry “Dubrovnik.” However, they reportedly sold the “Dubrovnik” in April, and are no longer operating the Bari-Bar route.
Then there were reports that the Bar ferry port operator “Barska Plovidba” was entering into a contract for the ferry “Ionian Star” to operate the route this summer. At some point the planned Italian port apparently was shifted from Bari to Brindisi, and a schedule was published in June. But later in June it was announced that the arrangement with the Ionion Star’s owners had been cancelled.
Most recently it has been said that Barska Plovidba is trying to buy one, or maybe even two, ferries of its own to operate the route. “A/F Francesca” has been mentioned as a possibility. However, that sale supposedly won’t take place until the fall, and right now the Francesca is still on the Bari-Durres (Albania) route.
In short, as far as I can tell from thousands of miles away, there is no Bari-Bar ferry this summer. Unless you can find out definitively that I’m wrong, you should plan to sail from Dubrovnik.
You can read about the whole saga here: https://theferryforums.com/viewtopic.php?t=900