David wants to know if he's secure surfing the internet on his mobile device. Leo says that nothing is unhackable, but LTE is encrypted and very secure. A phone can be hacked, even at the radio level, though. It's also possible for someone to spoof his SIM card. But it's too much work for the average hacker. It would have to be a state level attack in order to accomplish it. Wi-Fi is less secure, and if he's relying on WPA2 or any other Wi-Fi connection, it's possible to hack it. But that's not easy, either. Odds are, there's really not all that much to worry about.
Eddie wants to know if Roku will look for a hotspot. Leo says it doesn't really matter, the Roku will look for Wi-Fi no matter where it is. But Eddie should remember that hotspots tend to have more restrictive bandwidth caps, and 1GB an hour is not surprising on Netflix.
Charles and his family are going on a cruise and want to know if his devices need to run through a VPN. Leo says there are some risks, but not as much on an iPad. Google has been pushing for https everywhere, meaning that his search activity is encrypted. But that's not stopping someone from using a Wi-Fi sniffer called a Pineapple or Wireshark to figure out what his access point name is. A wise thing to do would be to forget his home network before he goes. Another option is the Tiny Hardware Firewall.
Nicholas has a Samsung Galaxy S6 Edge Plus and he's complaining that his hotspot Wi-Fi speed is too slow. Leo says that may be a limitation of the hotspot software. It could be deliberate on the part of the wireless company as well. That's why he advises getting a MiFi card as a dedicated hotspot. It's likely the carrier that's slowing him down.