Is the entire system RAM available on the router?
Is the entire system RAM available on the router?
There is a later beta version that you could try flashing, but this would be using a manual flash (download file, upload file to router through interface, wait for flash). Do it in this order before setting it up as you want... FULL RESET —> FIRMWARE FLASH —> FULL RESET Also, try running 1 of the devices in regular router mode (not AiMesh) to see how it behaves. The next thing to do would be to SSH into the router and extract the log files to see what is causing the NVRAM to fill up so quickly. Googling those exact errors don’t seem to return any working solution, unfortunately. Hopefully, someone else has input. If the problem continues to occur after a regular number of days, you could put the units on a power-cycle schedule just before that happens to clear the NVRAM.
I experienced the same router problem this morning. The system log showed the message: WAN Connection: ISP's DHCP did not function properly. The issue wasn't with my modem since a direct connection worked fine. After several reboots, the problem would appear again temporarily. I examined the logs and found an entry for dnsmasq-dhcp[1439]: failed to write /var/lib/misc/dnsmasq.leases: No space left on device (retry in 60s). I turned SSH access on and checked disk space using "df -h". It looked like /var was almost full. Without knowing what to clear, I decided to perform a hard reset. I powered off the router, held the WPS button, waited for it to power back on, then released the button. After turning it back on, I followed the setup guide, installed the latest firmware, and verified the disk space was now at 0%. I’m not sure why this resolved the issue, but I think I explained what helped me.
I had a similar issue this morning with my RT-AX55 router (latest firmware version 3.0.0.4.386_51598). It was connected but didn’t have internet access. I tried connecting directly to the Ethernet cable from my FiOS setup, and it worked perfectly. After rebooting for about 8-10 minutes, the web interface became very slow and started showing the same error messages you mentioned: “failed to write dnsmasq.leases: No space left on device,” plus many “out of memory” and firewall issues. This usually happens around the time the unit starts reporting DNS problems on any connected devices before losing connection completely.
I hadn’t changed any settings beyond setting the SSID and password a year ago, and it had been functioning well for over a year with only ten devices connected. It seems something unusual on the ASUS side might have caused storage issues or corrupted logs, filling up the device until a factory reset was needed. I didn’t set up SSH access since I suspected the storage was full. After performing a factory reset, everything worked smoothly for more than ten minutes.
Post-reset, CPU and RAM usage dropped significantly—booting to just 65-66% RAM with minimal CPU activity, compared to the previous 79% RAM and high usage before. It’s unclear what caused these changes, but I’m curious if this will repeat next year.
I'm experiencing the same issue today (17 May 2023) after roughly a year without any problems. Everything seems to be using the factory default configuration. No extra features were turned on—just the standard firewall enabled without any logs being saved. Before restarting, the router couldn't reach the internet even though it connected directly to the fiber line. Accessing the Asus UI at router.asus.com reveals one CPU stuck at 100% and errors in the logs: May 17 09:18:05 dnsmasq-dhcp[1127]: failed to write /var/lib/misc/dnsmasq.leases – no space left on device (retry in 60s). Restarting the ASUS RT-AC86U temporarily resolved the problem for a short period: df -h /var shows ample space, but tmpfs appears to be filling up unexpectedly (memory mount instead of actual disk). The system is running firmware 3.0.0.4.386_48260-gd4c241c. It's strange that this started affecting several users today. I prefer not to wipe and reload. If anyone else finds a solution, please share. Thank you! Edit: Updated to firmware 3.0.0.4.386_51529-g70acb9d and waiting anxiously for it to return. # while true; do df -h; sleep 10; done Filesystem Size Used Available Use% Mounted on tmpfs 215.1M 184.0K 214.9M 0% /var Presumably a bug is causing tmpfs to fill in memory instead of using disk. I'm on firmware 3.0.0.4.386_48260-gd4c241c. It's unusual this started happening to multiple of us today. I'd rather not reset everything. If someone else has a fix, let me know. # while true; do df -h; sleep 10; done Filesystem Size Used Available Use% Mounted on ubi:rootfs_ubifs 77.2M 63.4M 13.7M 82% / devtmpfs 207.9M 0 207.9M 0% /dev tmpfs 208.1M 192.0K 207.9M 0% /var tmpfs 208.1M 912.0K 207.2M 0% /tmp/mnt mtd:bootfs 4.4M 3.3M 1.1M 75% /bootfs tmpfs 208.1M 912.0K 207.2M 0% /tmp/mnt mtd:data 8.0M 584.0K 7.4M 7% /data tmpfs 208.1M 912.0K 207.2M 0% /tmp /dev/mtdblock9 47.0M 2.9M 44.1M 6% /jffs Edit: I have two ASUS RT-AC86U units. The one updated to firmware 3.0.0.4.386_51529-g70acb9d is no longer affected. The other still using the old firmware 3.0.0.4.386_48260-gd4c241c keeps the issue. Edit: Stable for over an hour now with the latest firmware. Previously, the problem would return every 10–15 minutes. Edited May 18, 2023 by asussuss – added firmware upgrade info
I'm experiencing issues with my RT-AX92U this morning. The firmware version I'm using is 3.0.0.4.386_46061, while the latest available on ASUS is 3.0.0.4.388.22525. Updates via automatic or manual methods haven't worked today. Similar problems occurred on May 17 at 21:24:31 when dnsmasq-dhcp failed to save a lease file due to space issues, prompting repeated retries after 60 seconds. After this incident, other warnings appeared inconsistently—such as watchdog alerts about DST time changes and multiple firewall restart notifications. The NTP server in system settings is set to "pool.ntp.org," which seems default but hasn't been adjusted recently. This pattern suggests possible instability with time synchronization or network configuration.
Hey everyone, I'm experiencing the same problems with my two RT-AX92U routers in mesh mode. They're running firmware 3.0.0.4.386_46061 on the 2.0 RT-AX92U model. I haven't managed to access the router during crashes to check RAM and CPU usage. I'm hoping for a quick response and might file a support case.