Time Capsule replacement

Unless you want to consider purchasing another Time Capsule, you will have to drop the requirement of a router with a built-in hard drive, since the Time Capsule is a one-of-a-kind product.

Last time I checked earlier today, Time Capsules were still available from Apple online and in the stores (at full price) in both 2 TB and 3 TB versions. A new Time Capsule should go 4-5 years or so.

If you don't want to purchase another Time Capsule, then an AirPort Extreme router will support Time Machine backups to a USB drive attached to the AirPort router. Be advised though, that this combination is significantly slower than a Time Capsule with Time Machine.

After that, some Arris and Netgear routers will support an attached USB drive for file sharing. Whether or not Time Machine backups will work well with a given model is open to question. You will have to get with the support folks at Arrris or Netgear to ask if a given router will support Time Machine. Some will...and some won't.

A Network Attached Storage device (NAS) like Synology will support Time Machine backups, but a NAS is not a router.

Another thought perhaps......the simplest, fastest, least expensive, and most reliable way to back up using Time Machine would be to connect a USB drive directly to your Mac.

Arris and Netgear routers

Did you mean Arris or Asus Bob.. AFAIK no Arris routers support TM.. the Asus does.

To jog4joy

Sounds like a mild form of masochism..

I am doing test backups to an Asus router with USB 3 drive plugged in. For now I would call it tricky to get right.

Then again since Sierra TM is hardly reliable to network targets including Time Capsule.. but Bob is correct.. if you really want a new one now grab end of stock Time Capsule.

Test backups to a Synology NAS going very well and very reliable. But the outlay is very heavy .. so you need to be prepared to spend a bit of money and the synology is not justified for purely backup target. You need to be using file serving or other functions as well.

Thinking one thing and typing another. Asus it is.