Secondary ASUS-AC87U Keep Disconnecting

[huntersfo]

Hello,

I am using an ASUS-AC87U with latest merlin firmware, in a LAN environment, to have extra layer protection. The original ASUS firmware does not seem to support to plug in a LAN switch port as WAN port. So I flashed a Merlin firmware, with static IP configured. I have a few ASUS AC87U recently configured like this and all are experiencing the same issue.

After setup completion, all devices under this router, keep disconnecting.

I would appreciate it if you could advise the possible causes and how to fix it.

Here is the ping output of the Windows attached to this network.
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=14ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Request timed out.
Reply from 172.217.164.110: bytes=32 time=5ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48
Reply from 172.217.164.110: bytes=32 time=4ms TTL=48

 

[huntersfo]

Just add some background testing.

When I remove this router, and directly connect the computer to the switch port, everything seems fine without disconnection. The switch is a Cisco catalyst and the WAN connection is via another set of switch/router/modem.

The AC87U connection issue happens on both wire and wireless. The above test ping command is in a wire connection from Windows to AC87U.

I also tested ping command from AC87U Network Tool-Network Analysis. It shows 54% packet loss from ping command.

PING google.com (172.217.8.14): 56 data bytes
64 bytes from 172.217.8.14: seq=0 ttl=46 time=121.519 ms
64 bytes from 172.217.8.14: seq=1 ttl=46 time=69.320 ms
64 bytes from 172.217.8.14: seq=2 ttl=46 time=68.977 ms
64 bytes from 172.217.8.14: seq=3 ttl=46 time=68.784 ms
64 bytes from 172.217.8.14: seq=4 ttl=46 time=69.147 ms
64 bytes from 172.217.8.14: seq=5 ttl=46 time=68.951 ms
64 bytes from 172.217.8.14: seq=34 ttl=46 time=69.012 ms
64 bytes from 172.217.8.14: seq=35 ttl=46 time=68.564 ms
64 bytes from 172.217.8.14: seq=36 ttl=46 time=68.787 ms
64 bytes from 172.217.8.14: seq=37 ttl=46 time=69.071 ms
64 bytes from 172.217.8.14: seq=38 ttl=46 time=69.069 ms
64 bytes from 172.217.8.14: seq=39 ttl=46 time=68.789 ms
64 bytes from 172.217.8.14: seq=40 ttl=46 time=68.763 ms
64 bytes from 172.217.8.14: seq=41 ttl=46 time=68.760 ms
64 bytes from 172.217.8.14: seq=42 ttl=46 time=69.079 ms
64 bytes from 172.217.8.14: seq=43 ttl=46 time=68.966 ms
64 bytes from 172.217.8.14: seq=44 ttl=46 time=68.798 ms
64 bytes from 172.217.8.14: seq=45 ttl=46 time=68.835 ms
64 bytes from 172.217.8.14: seq=46 ttl=46 time=68.785 ms
64 bytes from 172.217.8.14: seq=47 ttl=46 time=69.121 ms
64 bytes from 172.217.8.14: seq=48 ttl=46 time=68.775 ms
64 bytes from 172.217.8.14: seq=49 ttl=46 time=68.745 ms
64 bytes from 172.217.8.14: seq=50 ttl=46 time=68.763 ms
64 bytes from 172.217.8.14: seq=51 ttl=46 time=68.726 ms
64 bytes from 172.217.8.14: seq=77 ttl=46 time=68.857 ms
64 bytes from 172.217.8.14: seq=78 ttl=46 time=68.847 ms
64 bytes from 172.217.8.14: seq=79 ttl=46 time=69.002 ms
64 bytes from 172.217.8.14: seq=80 ttl=46 time=69.127 ms
64 bytes from 172.217.8.14: seq=81 ttl=46 time=68.768 ms
64 bytes from 172.217.8.14: seq=82 ttl=46 time=68.774 ms
64 bytes from 172.217.8.14: seq=83 ttl=46 time=68.801 ms
64 bytes from 172.217.8.14: seq=84 ttl=46 time=68.799 ms
64 bytes from 172.217.8.14: seq=85 ttl=46 time=68.759 ms
64 bytes from 172.217.8.14: seq=86 ttl=46 time=72.223 ms
64 bytes from 172.217.8.14: seq=87 ttl=46 time=68.820 ms
64 bytes from 172.217.8.14: seq=88 ttl=46 time=68.848 ms
64 bytes from 172.217.8.14: seq=89 ttl=46 time=68.795 ms
64 bytes from 172.217.8.14: seq=90 ttl=46 time=68.826 ms
64 bytes from 172.217.8.14: seq=91 ttl=46 time=68.919 ms
64 bytes from 172.217.8.14: seq=92 ttl=46 time=68.769 ms
64 bytes from 172.217.8.14: seq=93 ttl=46 time=68.816 ms
64 bytes from 172.217.8.14: seq=94 ttl=46 time=69.093 ms
64 bytes from 172.217.8.14: seq=95 ttl=46 time=68.796 ms
64 bytes from 172.217.8.14: seq=96 ttl=46 time=68.892 ms
64 bytes from 172.217.8.14: seq=97 ttl=46 time=68.794 ms
--- google.com ping statistics ---
99 packets transmitted, 45 packets received, 54% packet loss
round-trip min/avg/max = 68.564/70.120/121.519 ms

 

[huntersfo]

Hi All,

I read some posts and realized that the issue seems to be that ASUS routers do not support cascade router, or LAN-LAN mode.

Like Linksys does support LAN-LAN mode:
https://www.linksys.com/ca/support-article?articleNum=132275

Could you help to confirm if this is the case? Is there anyway to setup the ASUS AC87U to support LAN-LAN mode?

Thank you in advance!

 

[joegreat]

I read some posts and realized that the issue seems to be that ASUS routers do not support cascade router, or LAN-LAN mode.

This was also my first thought: You are putting router on router and home devices are not made for this network setup.

I would try to add Spanning-Tree Protocol to the scenario (on all routers) - on the AC87U you can find it under LAN / Switch Control.
Not sure this will help, but it's worth a try - do not forget to restart your setup (one be one with power down).

 

[huntersfo]

This was also my first thought: You are putting router on router and home devices are not made for this network setup.

I would try to add Spanning-Tree Protocol to the scenario (on all routers) - on the AC87U you can find it under LAN / Switch Control.
Not sure this will help, but it's worth a try - do not forget to restart your setup (one be one with power down).

Thank you Joe!

I did disable NAT Acceleration and enable Spanning-Tree Protocol and it seems working properly now!

It seems the ASUS AC87U router works better with Cisco switches, but not those low-end TP-Link switches.