The Tomato Shibby firmware v140 is the best router firmware ever built. It is so crazy stable and has alot of routing goodness packed into this little unit it's just crazy good.
Specs
Firmware: Tomato Firmware 1.28.0000 -140 K26ARM USB VPN-64K
Router: Asus RT-AC68R/U
Devices Menu
This devices menu page alone is stacked with some great data. Data on all the devices connected to the router (easy to spot any unwanted guests), signal quality of each device connected and the noise level measured in dBm, and the send/receive rate of each device.
Bandwidth Monitoring
A graphical representation of your daily bandwidth usage by networking interface. You can hover over the graph to see usage for that particular day and time.
The weekly/monthly bandwidth monitoring gives you a nice glimpse into your data usage over those periods. You have the option to store all this data goodness on the router itself or attaching a USB drive via one of the two USB ports on the router. I have data dating back as far as 2015 on the USB drive.
Not sure what I would ever need data dating back to 2015 but in a shorter turn-around you can always pull the data to see what might be misconfigured incase there were some issues.
The firmware permits setting up virtual wireless AP on the router to route traffic through the virtual AP. In our case I have set up a guest network using the virtual wireless AP.
The virtual wireless is tied to the 2.4GHZ radio and has it's own ip bracket. With this in place, I tunnel all my traffic on the 5GHZ radio through the VPN (more on VPN below), block users connected to the guest wireless from connecting to any local network services, I could apply QOS on the traffic to limit bandwidth usage, or network protocol usage.
You are able to setup two VPN clients on the router or two VPN servers. I have currently setup a single VPN client and am channeling all traffic connected to the 5GHZ radio through the VPN. You are able to achieve this simply using the routing policy interface and assigning a ip, a bracket of ip's to not go through the VPN tunnel.
In our case, I have all traffic on the 2.4GHZ radio to not tunnel through the VPN. I travel constantly and this helps in connecting my Apple TV to the 2.4GHZ network (non-VPN tunnel traffic) for my Netflix goodness and avoiding the "we see you are using an anonymous proxy" dreaded message.
Conclusion
The tomato shibby v140 on the Asus RT-AC68R is the most stable combination I have had on a router. I have been through it all, the Linksys WRT54GL from back in the day to the N routers, and now the AC. We have only scratched the surface above on the plethora of options available.
If you are considering setting up a stable home network where you never want to touch the router after its setup, but know if there was a new requirement to do something your router will have your back, then this is the winning combination.