Mine is also less than a foot away and has been for a year without interference issues.
Another thing, depending on what gets rebooted and the timing of how long things are powered off, it’s possible that either the ST Zigbee channel on the hub changed upon startup, or rebooting the router changed what channel the 2.4ghz band is on. Troubleshooting these things 1 by 1 to isolate the actual issue can help you prevent these same issues in the future. Otherwise it will always remain a guessing game. Was it my hub distance to router, was it my 2.4ghz channel being on 1 and interfering with neighbors router, was it my Zigbee channel interfering with my wifi 2.4ghz channel (overlap), or did my Hue Bridge channel cause some sort of interference between the other two?
A lot of people, depending on equipment and setup don’t run into these issues, but for those that do experience something like this, troubleshooting all these scenarios is worth trying to track down to prevent it from happening again.