I'm glad I found this thread! The local network in my home now works as it should
My setup
- DSL modem: ASUS DSL-AC55U
- Mesh routers: 2x ASUS RT-AC59U V2 - turned out that Wi-Fi on the DSL modem didn't reach far enough due to placement of the wall socket in one far corner of the apartment, the number of walls, and mirrored wardrobes in the apartment so had to get two mesh routers!
Summary (TL;DR)
The main RT-AC59U V2 was at 100% CPU all the time. After I ssh'd to
router.asus.com and ran
top, I could see that
nt_center was trying to take 100%, although some other processes were able to grab around 4% so
nt_center was sitting at around 96%. I deleted the
/jffs/.sys/nc/nt_center.db file, rebooted the router and all has been well since. The web interface continues to show information from the devices so the appropriate icons are shown: lights, laptops, Linux penguin, cameras, printer, etc. The device names are also shown correctly. No more connection drop-outs and Apple HomeKit doesn't have devices randomly not responding.
More detailed info
What problems was I experiencing?
Due to 100% CPU usage on the main router, the main problems I was experiencing were:
- Connection drops:
- LIFX lights would not stay connected
- Apple Siri would try to send information to my iPhone but would give up saying it couldn't find it
- BroadLink infrared blaster would sometimes work, sometimes not
- Router logon page (
) wouldn't load and browser would eventually give up
- Router couldn't accept an SSH connection because the router was too busy
What did I try?
Without the ability to logon to the router via the web interface or ssh, I tried many things, such as rebooting the router, resetting the router, disconnecting the second router from the mesh network and setting it up again. Nothing worked.
How did I get ssh to work?
After rebooting the main router, I had to connect to it via ssh immediately upon it rebooting. If I waited up to 30 seconds after it had booted, the router wouldn't respond via the browser or ssh since it was already running at 100% CPU. So I made sure I knew its IP address, which I fixed via the DSL modem/router, and then power cycled it and kept trying to connect to it while it was starting up until it let me in.
How to ssh to the ASUS router?
Command below with default username of admin:
ssh -vvv admin@router.asus.com
What did I when I could login via ssh?
After logging in, I issued the
top command, saw that nt_center was taking at least 96% CPU. I quit out of
top by pushing the
q key and typed
kill -SIG 1 476 (-SIG 1 = TERMinate and 476 is the process ID so you would need to change this to whatever process ID you have). As soon as the process was killed, it restarted with a new and different process ID and took 96% of the CPU again. Killing only the process will not help so I needed a different solution.
Solution
That's when I found this thread and realised I needed to delete the /jffs/.sys/nc/nt_center.db file. I was hesitant because it was such a big file but bit the bullet and now it's done. The CPU now hovers between 4% and 26% when being watched and the web interface shows the same, which is expected. The nt_center process now runs between 2% and 4% CPU, which is muuuuuuch better. All devices remain connected, LIFX has no problems, Apple HomeKit has no problems and connections on the LAN between devices is immediate.