Time to build some Network attached storage. Yes there are a lot of ways to back up but mostly I've been hanging a USB hard drive off a router and using that is certainly better than nothing but what happens if the drive breaks. You buy a new hard drive and start all over again which takes time provided you still have the original stuff that you wanted to back up in the first place.
Having a mirrored NAS means if one drive fails the other drive is mirrored and you just swap in a new drive. It costs a bit more but the amount of storage increases a lot not to mention the speed and the integrity of the backups. Still a good idea to use a USB hard drive and carry it to work for an off site back up.
The best way to build a NAS is to take an old computer or in this case a new computer and install an OS called FreeNAS on it. FreeNAS is as the name implies. Free. Basically what you need is a server motherboard. A good Intel enterprise type CPU and a couple of hard drives (or more).
I opted for a Lenovo TS140 which is a case, motherboard, and CPU with 16 GB of memory. More than enough and not a bank breaker.
Next is a couple of Enterprise NAS hard drives. Don't buy the cheapest hard drive there is. You'll regret it. The darling of the FreeNAS community seems to be Western Digital "Red" Hard Drives. I picked up a couple 4TB ones that were WD refurbished (yeah, I know.....we'll see).
Now to install the OS you need another hard drive or to keep it simple and cheap you can boot and run FreeNAS from a USB stick that is 8GB or larger in size. In fact that seems to be how a lot of folks are doing it. And you can set up 2 USB sticks to mirror each other to keep it redundant should one fail.
I haven't yet started this project but it looks like a fun one.