What was your daily pax level? In my opinion, while you can start to feel the effects with just a few hundred thousand, you really need > 1m daily pax. Also only 4 hubs aint much. Try 40. Hub EVERY airport you fly to/from. I general only focus on green pax at standard capacities & prices till I get to this sort of level. Then I go nuts. It takes a lot of planes & a lot of time. Good luck.
The site's been boken in a number of places for some time now. My son who's studying IT at university had a look "under the hood" & identified a number of coding issues within seconds. All game worlds function but some better than others it seems. But yeah, maps seem to be too hard for it now.
Recovering full-blown addict here. All I can say is "dream on". People have been suggesting this since I started playing here 11 years ago. I think I was even one of them. It's a miracle this game's still even functioning.