Do you have SSH access to the router enabled?
LAN only or
LAN & WAN?
It would helpful if you could SSH into the router and post the output from these commands:
SSH Only Lan.
removed some sensitive data from the output here
ls -altr /tmp/:
drwxr-xr-x 4 'username' root 80 Dec 31 1969 var
drwxr-xr-x 2 'username' root 40 Dec 31 1969 share
-rw-r--r-- 1 'username' root 0 Dec 31 1969 settings
drwxr-xr-x 3 'username' root 60 Dec 31 1969 notify
drwxr-xr-x 2 'username' root 40 Dec 31 1969 inadyn.cache
drwxr-xr-x 3 'username' root 60 Dec 31 1969 home
-rw-r--r-- 1 'username' root 9 Dec 31 1969 misc.json
drwxr-xr-x 3 'username' root 60 Dec 31 1969 confmtd
-rw-rw-rw- 1 'username' root 506 May 5 2018 wl1_hapd.conf
-rw-rw-rw- 1 'username' root 1264 May 5 2018 wl0_hapd.conf
drwxrwxrwx 2 'username' root 40 May 5 2018 netool
-r-sr-x--- 1 'username' root 0 May 5 2018 ebtables.lock
drwxrwxrwx 2 'username' root 100 May 5 2018 dm
-rw-rw-rw- 1 'username' root 0 May 5 2018 awsiot_log
drwxrwxrwx 3 'username' root 80 May 5 2018 avahi
drwxrwxrwx 2 'username' root 80 May 5 2018 asdfile
-rw-rw-rw- 1 'username' root 0 May 5 2018 asd.init
-rw-rw-rw- 1 'username' root 64 May 5 2018 lld2d.conf
lrwxrwxrwx 1 'username' root 8 May 5 2018 ipsec_updown -> /sbin/rc
drwxrwxrwx 2 'username' root 40 May 5 2018 asusfbsvcs
-rw-rw-rw- 1 'username' root 355 May 5 2018 run_lldpd.sh
-rw-rw-rw- 1 'username' root 0 May 5 2018 mastiff_log
-rw-rw-rw- 1 'username' root 5 May 5 2018 mastiff.pid
-rw-rw-rw- 1 'username' root 64 May 5 2018 lldpd_bind_ifnames
-rw-rw-rw- 1 'username' root 4286 May 5 2018 lighttpd.conf
drwxr-xr-x 2 'username' root 40 May 5 2018 cfg_mnt
lrwxrwxrwx 1 'username' root 8 May 5 2018 zcip -> /sbin/rc
lrwxrwxrwx 1 'username' root 8 May 5 2018 wpa_cli -> /sbin/rc
lrwxrwxrwx 1 'username' root 8 May 5 2018 udhcpc_wan -> /sbin/rc
lrwxrwxrwx 1 'username' root 8 May 5 2018 dhcp6c -> /sbin/rc
-rw-r--r-- 1 'username' root 56 May 5 2018 relist.json
-rw-rw-rw- 1 'username' root 92 May 5 2018 obvsie
-rw-rw-rw- 1 'username' root 1 May 5 2018 obstatus
-rw-rw-rw- 1 'username' root 92 May 5 2018 guest_vsie
drwxrwxrwx 2 'username' root 60 May 5 2018 asusdebuglog
-rw-r--r-- 1 'username' root 72 May 5 2018 *****.cap
-rw-r--r-- 1 'username' root 31 May 5 2018 ****.bi
-rw-rw-rw- 1 'username' root 411 May 5 2018 filter_ipv6.default
-rw-rw-rw- 1 'username' root 888 May 5 2018 filter.default
-rw-rw-rw- 1 'username' root 18 May 5 2018 rast_stc_idx1
-rw-rw-rw- 1 'username' root 18 May 5 2018 rast_stc_idx0
-rw-rw-rw- 1 'username' root 176 May 5 2018 chanspec_avbl.txt
-rw-r--r-- 1 'username' root 185 May 5 2018 aplist.json
-rw-r--r-- 1 'username' root 31 May 5 2018 *****.bi
-rw-r--r-- 1 'username' root 185 May 5 2018 ****.cap
drwxrwxrwx 5 'username' root 240 May 5 2018 lighttpd
-rw-r--r-- 1 'username' root 368 May 5 2018 *****.json
-rw-rw-rw- 1 'username' root 2445 May 5 2018 diag_port_status.json
-rw-rw-rw- 1 'username' root 10 May 5 2018 udhcpc0.expires
-rw-rw-rw- 1 'username' root 1094 May 5 2018 nat_rules__eth0
-rw-r--r-- 1 'username' root 43 May 5 2018 maclist.json
drwxrwxrwx 2 'username' root 600 May 5 2018 err_rules
-rw------- 1 'username' root 285 May 5 2018 wan0_ppp.env
drwxrwxrwx 3 'username' root 320 May 5 2018 ppp
drwxrwxrwx 20 'username' root 1776 Apr 26 16:29 ..
-rw-rw-rw- 1 'username' root 469 Jul 31 22:34 release_note0.txt
-rw-r--r-- 1 'username' root 43 Oct 21 09:31 resolv.dnsmasq
-rw-r--r-- 1 'username' root 51 Oct 21 09:31 resolv.conf
-rwxrwxrwx 1 'username' root 1204 Oct 21 09:31 ipsec_iptables_rules
-rw-rw-rw- 1 'username' root 0 Oct 21 09:31 aaews_log
-rw-rw-rw- 1 'username' root 5 Oct 21 09:31 aaews.pid
drwxrwxrwx 2 'username' root 180 Oct 21 09:31 nc
-rwx------ 1 'username' root 0 Oct 21 09:31 .bwdpi.rule.lck
-rwx------ 1 'username' root 0 Oct 21 09:31 .bwdpi.appdb.lck
-rw-rw-rw- 1 'username' root 262188 Oct 21 09:31 syslog.log-1
-rw-rw-rw- 1 'username' root 1438 Oct 21 09:31 redirect_rules
-rw------- 1 'username' root 1264 Oct 21 09:31 nat_rules_ppp0_eth0
lrwxrwxrwx 1 'username' root 24 Oct 21 09:31 nat_rules -> /tmp/nat_rules_ppp0_eth0
-rw-rw-rw- 1 'username' root 6305 Oct 21 09:31 filter_rules
-rw-rw-rw- 1 'username' root 19 Oct 21 09:32 hw_auth_clm
-rw------- 1 'username' root 205 Oct 21 09:33 sig_upgrade.log
-rw-rw-rw- 1 'username' root 65770 Oct 21 09:38 ce0.log.bak
-rw-r--r-- 1 'username' root 263 Oct 21 09:40 wchannel.json
-rw-r--r-- 1 'username' root 398 Oct 21 09:40 chanspec_private.json
-rw-r--r-- 1 'username' root 232 Oct 21 09:40 chanspec_avbl.json
-rw-r--r-- 1 'username' root 854 Oct 21 09:40 chanspec_all.json
drw------- 3 'username' root 480 Oct 21 10:06 bwdpi
drwxrwxrwx 3 'username' root 60 Oct 21 10:09 mnt
-rw-rw-rw- 1 'username' root 15758 Oct 21 10:29 ce0.log
-rw-rw-rw- 1 'username' root 200 Oct 21 10:30 webs_upgrade.log
drwxr-xr-x 12 'username' root 1760 Oct 21 10:48 etc
-rw-rw-rw- 1 'username' root 0 Oct 21 10:49 syscmd.log
-rw-rw-rw- 1 'username' root 3987 Oct 21 10:49 apscan_info.txt
-rw-r--r-- 1 'username' root 846 Oct 21 10:49 allwclientlist.json
-rw-rw-rw- 1 'username' root 8841 Oct 21 10:50 syslog.log
-rw-rw-rw- 1 'username' root 3510 Oct 21 10:51 usb.log
drw-rw-rw- 2 'username' root 280 Oct 21 10:51 .diag
-rw-rw-rw- 1 'username' root 3496 Oct 21 10:51 dev
drwxrwxrwx 24 'username' root 1940 Oct 21 10:51 .
-rw------- 1 'username' root 791 Oct 21 10:51 MON_CHECK_
-rw-r--r-- 1 'username' root 3144 Oct 21 10:52 clientlist.json
-rw-r--r-- 1 'username' root 59 Oct 21 10:52 ********.port
-rw-r--r-- 1 'username' root 1451 Oct 21 10:52 wiredclientlist.json
-rw-r--r-- 1 'username' root 721 Oct 21 10:52 current_wired_client_list.json
drwx------ 2 'username' root 60 Oct 21 10:52 db
-rw-rw-rw- 1 'username' root 0 Oct 21 10:52 watchdog_heartbeat
-rw-r--r-- 1 'username' root 45045 Oct 21 10:52 nmp_cache.js