I have 2x SSID, one for 2,4GHz and one for 5GHz.
2,4GHZ always shows up instantly, 5GHz on the other hand usually takes a while, some times several minutes, and once in a while (rarely), i just have to boot the computer before it will eventually show up after some waiting. It's always been like this as long as I can remember. OS reset does not fix the problem, nor booting router/modem.
I have a surface pro 2 that doesn't have the same problem after starting up. I also have a third computer from work that I bring home some times and that does also not have this problem.
Just took the time, from boot it took exactly 4 minutes and 40 seconds before 5 box showed up. As mentioned before it varies how long it will take. Sometimes it seems to be almost instantly or max 10-20 seconds.
Problem computer (custom build)
Intel 7260 AC
Windows 10
Driver version 17.15.0.5
Driver date 22.02.2015
Also added: ScanWhenAssociated (DWORD 0) to the 7265 registry container to avoid spikes. I think this setting is for disabling wifi roaming.
I just recently upgraded this to version 18.33.3.2 (date 03.05.2016) with no sign of improvements.
Link score (inssider): 100
4/4 bars (system icon)
Surface pro 2 (no problem on this computer)
Marwell network card
Windows 10
Link score: haven't checked.
3/4 bars (system icon)
Problem computer number 2 - Work laptop (HP)
Intel 7265 AC
Windows 10
Driver version 18.32.1.2
Driver date 30.12.2015