Devices like routers, modems, etc... come with wall mount holes.
Every device come with different size and spacing. when we change a router to different make/model, new holes need to be drilled (if the mount hole spacing does not match with previous one). this is a problem of aesthetics too.
I would prefer all the devices come with iron type of metal back. and walls to be fixed with a strong magnetic sheet (strong enough to hold say 25g/sq.Inch).
Just stick all your devices !!!
Note: This will be useful to electronic devices only if magnetism does not interfere with their functionality.
This can be used for all non-electronic devices.
Note: size of metal back of the device should be as per the weight of the device in the view of magnetic strength of sheet (x grams/ unit area should be standardized)