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Ac68u not getting an ip from DHCP

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wollyka

Occasional Visitor
I have an Ac68u plugged into an adsl modem (technicolor 582 tg). The modem is only in full bridge mode with dhcp.
The router is in 192.168.2.xxx and the modem is set as 192.168.1.1.
Things were working, the router gets two ips, a wan ip from the ISP and an ip in the range of 192.168.1.x from the modem. That's way I can access my modem through my Lan (192.168.2.xxx).

I had to change my modern to linksys x1000 (also used in full bridge mode). I configured it the same way. However, it seems when I had to power off the router or modern for whatever reason, the ac68u isn't getting a ip from the modem. The wan ip is fine from the ISP. So I cannot access the modem directly without plugging a Lan into it with an ip in the range of 192.168.1.x. If I restart the dhcp server on the modem, then everything works well again. It looks like the ac68u is not sending a dhcp client request to the modem.
Is there a way to get the ac68u send a request? Or give it a fixed ip on the wan side plus getting an automatic one from the ISP?
Thanks
 
Another question :how can I force the dnsmasq service to restart after x minutes after a boot /reboot?
 
I have an Ac68u plugged into an adsl modem (technicolor 582 tg). The modem is only in full bridge mode with dhcp.
The router is in 192.168.2.xxx and the modem is set as 192.168.1.1.
Things were working, the router gets two ips, a wan ip from the ISP and an ip in the range of 192.168.1.x from the modem. That's way I can access my modem through my Lan (192.168.2.xxx).

I had to change my modern to linksys x1000 (also used in full bridge mode). I configured it the same way. However, it seems when I had to power off the router or modern for whatever reason, the ac68u isn't getting a ip from the modem. The wan ip is fine from the ISP. So I cannot access the modem directly without plugging a Lan into it with an ip in the range of 192.168.1.x. If I restart the dhcp server on the modem, then everything works well again. It looks like the ac68u is not sending a dhcp client request to the modem.
Is there a way to get the ac68u send a request? Or give it a fixed ip on the wan side plus getting an automatic one from the ISP?
Thanks

Not all modems in 'bridge' mode can be accessed from the LAN.

However when I was on ADSL I used this technique of wan-start....

Code:
   # Access to the TP-LINK TD-8816 ADSL modem (whilst in bridge mode)can be extremely useful to check statistics/line noise/errors etc.
   # NOTE: nat-start script is also required!!!

   # TP-LINK TD-8816 default I/P address is 192.168.1.1 so we need to define 192.168.1.2

   # So now we have (a minimum of) two subnets; Martineau LAN (10.88.8.*) and DSL Modem (192.168.1.*) 
   # If it doesn't work, then sometimes  a modem will only serve its web interface to devices on the same subnet.
   # You could try to change the modem's subnet mask to 255.255.254.0 (or 255.255.0.0), maybe that helps. 

   logger -t "($(basename $0))" $$ Adding ifconfig for Martineau TP-LINK TD-8816 ADSL modem : 192.168.1.1
   ifconfig `nvram get wan0_ifname`:0 192.168.1.2 netmask 255.255.255.0


and nat-start

Code:
# Access to the TP-LINK TD-8816 ADSL modem (whilst in bridge mode) can be extremely useful to check statistics/line noise/errors etc.
# NOTE: wan-start script is also required!!!

# TP-LINK TD-8816 default I/P address is 192.168.1.1 so we must have defined interface 192.168.1.2 ...see wan-start
#logger -t "($(basename $0))" $$ Adding NAT route for Martineau TP-LINK TD-8816 ADSL modem : 192.168.1.1 `nvram get wan0_ifname` 

#iptables -t nat -I POSTROUTING -o `nvram get wan0_ifname` -j MASQUERADE

to assign a static I/P address to access the modem, whilst obtaining an automatic I/P from the ISP WAN.

Regards,
 
Another question :how can I force the dnsmasq service to restart after x minutes after a boot /reboot?

I suppose init-start could be modified to create a one-off cron job for X minutes in the future....

but a quick and dirty solution would be to have init-start simply sleep for the requested number of minutes...

e.g. int-start

Code:
sleep 150
sleep x * 60
service restart_dnsmasq


where I allow 150 secs for both of my routers to complete their normal boot process (seems to be correct), so you would add the appropriate wait X then restart the DNSMASQ service.

Regards,
 
Thanks Martineau, i will try it.
The linksys can be accessed in bridge mode, the problem is that its dhcp server is hanging so you need to restart manually to work!!
 
so i un-comment the following line in nat-start
iptables -t nat -I POSTROUTING -o `nvram get wan0_ifname` -j MASQUERADE

Edit: IT worked.. Thanks a LOT!
 
Last edited:

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