@Thubbert 

I would start with making sure the firmware is up to date and also modifying the wireless channel and width. Factory defaulting the router would be good to try as well if it has not been done yet. The 5GHz is very susceptible to interference from objects like walls so if you are at a distance test in the same room to see if it clears up. If there are no issues in the same room then where you'd want the 5GHz may be too far, but if it still happens then there may be an issue with the 5GHz antenna. 

A last test you can also try is to only have one device connected to the router to see if the drop happens. There could be another device hogging the bandwidth while it does an update or sync with the cloud (Dropbox/OneDrive).