I visited Hanoi three times in 2015. No problem meeting guys from the apps, some free or hotter looking guys for about 400-600k dong. Many of the money boys were quoting in $US.
Golden Cock gay bar closes at midnight and the police were outside to make sure it closed on time on the Saturday night that I went there. The locals at GC told me there are other clubs that stay open later so I will investigate further next time I go to Hanoi to find their location.
I prefer Ho Chi Minh City for more night life and met some great guys there from the apps. The nightclubs stay open to around 3am or later with the Republic gay disco and the mixed Apocalypse club very popular. Never had any problems taking a guy to the Apocalypse club. Most nights I would go to the walking street for amazing eye candy and later Bui Vien street for food and drinks.