From what I understand, 5Ghz doesn’t travel as far or through walls as well as 2.4Ghz. It can be improved by increasing the transmit power, if your router has such a setting.
As for travel, my main uses for a phone are:
- SMS/MMS (…and maybe a phone call or two)
- Maps/Navigation
- Camera
- Internet, to briefly check transport schedules, verify addresses of restaurants, museums, hotels, etc.
- Occasional use of specific commercial apps (airline, hotel, etc.)
- VPN service, to protect my browsing over public/hotel WiFi.
This all requires a modem and SIM card that will work in the region of the world I travel to, when going overseas. (I don’t like to rely on WiFi alone.)