Router/Version: Asus RT-N18U
Firmware: DD-WRT v3.0-r42925 std (04/18/20)
Kernel: Linux 4.4.219 #1336 Sat Apr 18 08:51:34 +04 2020 armv7l
Status: wan, lan, wifi, static dhcp, samba, usb and vap all work without visible issues.
Following appears in syslog. After few timeouts sync eventually succeeds.
Apr 19 05:58:02 dd-wrt daemon.debug ntpclient: Connecting to 126.96.36.199 [188.8.131.52]
Apr 19 05:58:02 dd-wrt daemon.err process_monitor: cyclic NTP Update failed (servers 2.pool.ntp.org 184.108.40.206 220.127.116.11)
Apr 19 06:58:05 dd-wrt daemon.debug ntpclient: Connecting to 2.pool.ntp.org [18.104.22.168] ...
Apr 19 06:58:08 dd-wrt daemon.debug ntpclient: Timed out waiting for 2.pool.ntp.org [22.214.171.124].
Apr 19 06:58:08 dd-wrt daemon.debug ntpclient: Connecting to 126.96.36.199 [188.8.131.52] ...
Apr 19 06:58:08 dd-wrt daemon.info ntpclient: Time set from 184.108.40.206 [220.127.116.11].
After much investigation, and replacing the power adapter along with changing outlets I have found that the intermittent reboots and slow downs is software related. I don't know which build the problem starts at but r42054 is running stable for me so it must be upstream of that. The syslog messages on r42925 after reboot don't look out of order from what others report here. Unfortunately papertrail doesn't pick up anything before the reboots or slowdowns happen, I'm thinking because the WAN connection halts before the problem is sent. If the devs are interested I can run a series of experiments to help distill the problem.