After determining that it was the external backup HD that causes crashes on my MacBook, I am consider (again) to use a NAS to backup over WiFi instead of a cabled one. Especially since my Macbook only has two USB-C ports, which are both taken (one for the power cord, one for the external monitor).
I know there are some entry-level (non-nerd) solution by WD, but I have also read that they can be hacked from the Internet, which is something I dread. I am looking to invest some money (500-ish USD) and I need to use it to backup my MacBook Air using TimeMachine. According to Apple, what I am looking for is: Network-attached storage (NAS) device that supports Time Machine over SMB (Server Message Block )
It seems that Synology offers a range of NAS devices that would fit the description, highly rated on Amazon. This articlehas a short review of the best options.
I'd like to buy it from the US and have it brought over with grabr or I will buy it this summer (European summer) when visiting home.