I think the business-travel milieu is the main obstacle here, though I can't rule out quirks of your psychology.

When I go to another city for pleasure rather than business, I find myself far more willing to approach people and the people I approach far more receptive. I don't know exactly why, and I don't know how well it generalizes, but I suspect it has something to do with mostly-subconscious differences in attitude driven by contextual explore/exploit wiring in my head. Big city vs. small town doesn't seem to make much of a difference, although some towns are friendlier than others. (For context, I'm neither particularly extroverted nor particularly introverted.)

Business travel is another story. Hotel bars for business travelers aren't geared toward random socialization in the first place, but more importantly I don't think they set off the same unfamiliarity signals, likely because cube farms and airports and midrange contemporary hotel bars look the same from Manila to Milan; it's less like conventional travel and more like a trip into the Business Class Dimension.

My advice: get out of the hotel, get out of the hotel district, and go looking on Yelp or the local equivalent for a popular night spot that suits your goals and personality. (I've had good luck near local universities; YMMV.) You won't be as hammered with unfamiliarity as you would be if you were traveling on your own time, but the locals won't be expecting interchangeable business travelers and you'll probably get a little further out of that headspace yourself.