Consider a bigger step:
Synology NAS. It has
Time Machine support (so you use it in the same way you use Apple's product now) and you can choose a model with up to many drive bays for more storage than you may ever need. It can even accommodate adding or upsizing drives on the fly so it can easily expand over time.
This will cost much more than a simple little single drive option like that Samsung but you'll probably eventually run through only 1TB, especially in a multi-computer household. Synology could grow to almost ANY size when you need more space... and bring many other nice options too like
shared storage, centralized
media storage, etc. I've had one for years and it works really well.
This will not cover the router want (it is not a router too), so you could continue using the Apple one until those wheels completely fall off or embrace ANY other router. Basically, you would be separating storage and Time Machine from the router as 2 distinct things.
During this time, you could leave the Apple Time Capsule functioning as Time Machine backup too. In other words, select both Time Capsule and Synology for TM backups and the Time Machine software would alternate backups between the two: TC on one backup, then Synology for the next. Since TM backups every hour, you can think of this as backing up to either piece of hardware every other hour (such as even hours on TC and odd hours on Synology). 2 distinct backups is much more secure than only 1. If TC conks, you'll still have a full TM backup on Synology at most only 1 hour, 59 minutes old.
If you still want both router and TM storage as one thing, seek out a new router with a USB port and check reviews to verify that attaching a drive to that port can deliver a good Time Capsule alternative.