RT-AX56U Secondary WAN DHCP

[sputnikk]

Hi All,

I'm trying to dedicate a port on my Asus to a secondary WAN connection going to a 4G backup router/modem. No matter what I do, I cannot get the ASUS to get DHCP from the 4G router or talk to it via static IP.

If I unplug the cable from the Asus backup WAN ethernet port and plug it into a laptop, I instantly get DHCP from the 4G router.

I've tried resetting the 4G router and make sure Asus is the first thing that touches it. I've tried cloning the mac address of my laptop. I've tried downgrading firmware on the ASUS.

I've even tried a crossover cable.

No matter what, ASUS reports "ISPs DHCP was not functioning properly". If I make it static ip in the known range of the 4G router (a separate /24 from the ASUS), I still can't access it. Even with a simple ping from ASUS terminal.

What god forsaken thing am I missing here?

Edit: ifconfig on the ASUS shows 0 TX packets for this interface?


RX packets:4294967978 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000


I know those are the stats to the correct ethX because of the cloned MAC address I gave it

 

[sputnikk]

admin@RT-AX56U-AFA0:/tmp/mnt/ASUSROUTER# tcpdump -i eth1 -XX -s0
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth1, link-type EN10MB (Ethernet), capture size 262144 bytes
18:39:56.039396 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from d4:25:8b:81:1b:08 (oui Unknown), length 300
0x0000: ffff ffff ffff d425 8b81 1b08 0800 4500 .......%......E.
0x0010: 0148 0000 0000 4011 79a6 0000 0000 ffff .H....@.y.......
0x0020: ffff 0044 0043 0134 df00 0101 0600 e73e ...D.C.4.......>
0x0030: a819 04a7 0000 0000 0000 0000 0000 0000 ................
0x0040: 0000 0000 0000 d425 8b81 1b08 0000 0000 .......%........
0x0050: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x0060: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x0070: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x0080: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x0090: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x00a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x00b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x00c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x00d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x00e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x00f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x0100: 0000 0000 0000 0000 0000 0000 0000 0000 ................
0x0110: 0000 0000 0000 6382 5363 3501 013d 0701 ......c.Sc5..=..
0x0120: d425 8b81 1b08 3902 0578 3709 0103 060c .%....9..x7.....
0x0130: 0f1c 212a f93c 0c75 6468 6370 2031 2e32 ..!*.<.udhcp.1.2
0x0140: 352e 3151 0e01 0000 6173 7573 2e72 6f75 5.1Q....asus.rou
0x0150: 7465 72ff 0000 ter...




Based on that tcpdump, I'm certainly requesting DHCP but not getting anything back.

1) it's odd that my own packet TX count won't go up and stuck at 0 when I see the ASUS creating packets. Also odd that RX packets are so high when there's nothing back whatsoever. Bug?

2) Odd that I'm not getting a response back when the same wire plugged into any other DHCP device gets an IP from the 4G router in 192.168.8.0/24 (the asus is serving 192.168.50.0/24)

 

[sputnikk]

I reflashed again, reset the 4G modem and remembered to on/off toggle the connection on the ASUS. It seemed to come up. Go figure.