Your findings are INcomplete. Best site for this and other similar: seat61.com
There are also as for now NO direct trains Bg->Zgr-there is also a fairly long and hard to bridge gap over the border Serbije-HRvatska.
In fact even reaching Bgr by rails is only possible for now from black mountains (cerna gora, Monte Negro), not from all surrounding other.
Bg->Bp is now -if you really insist on on the rails- in stead of a far better direct bus:
newly renovated and opened and NOT taking passes for now Bgr-N.Sad-thats just less as 1 hr.
Then 2 options: rail replacement bus, if it runs, not garanteed and taking just too long to reach onward connections, till Subotica.
Other report there is-hopefully-also a local tiny railcar from anOTHER stop in NS to Sub-said however to be often ´broke´.
Best way to bridge this gap is however a normal and thus payable bus direct-but then youd better just catch that bus in Bgr already.
From Sub 2/day MAV=HU combo of rail-repl bus till Szeged in the end (nice town btw-rec for a short stay, also very cheap), then hourly local MAV train to Bp (the gyors=fast section is free of RES, the IC=AC section needs to).
btw- these green buses now anywhere in EUR are FLIX and not flexi. easy to book/handle on their own app. Click on ´no ads´ unless you ant daily flows of that from them. FLIX also has settled in the Uk to compete with NatExpr
Thanks Mcdav.
Have you ever visited Belgrade. I was planning on going from Bar (Montenegro) to Budapest with a stop in Belgrade (and bus ( 6 hrs) to Budapest from ur advice) to break up the journey and was just wondering if this is worth it. My other option was travelling through croatia which I know also involves a bus.
would u recommend travelling through croatia or serbia from Montenegro to reach Budapest.
Thankyou