Was wondering if any of you tech savvy guys could give me some help with my network setup for home, i'd like to get some more opinions before I start replacing parts.

 

My current setup is a Motorola Surfboard SB6121 modem, which was paired with a cheap 20 dollar medialink router. It worked fine, but I just wanted something with some better range and some more options like network hard drive USB ports

 

I purchased a Asus NT-66 router as a replacement. 

 

Setup went fine, went through all the prompts and it connects, much better speed and range, But now the problem is the modem after a few minutes of browsing will restart, and then keep restarting indefinitely after it goes through its motions.

 

I need to unplug the modem , plug it back in, then it'll work again for a few minutes of browsing, then reboot and keep rebooting.

 

Now, this only happens with the new asus modem plugged in, if I plug the modem into my cheap medialink router everything works fine.

 

What might be the issue here ? 

 

 

So try a different router. I've been happy with the netgear ones. The other thing you can try is replace the modem, call the cable company, they tend to get new models every couple of years and they may want to replace it anyway

So try a different router. I've been happy with the netgear ones. The other thing you can try is replace the modem, call the cable company, they tend to get new models every couple of years and they may want to replace it anyway

I'd like to make this setup work.

 

I own the modem outright (screw rental fees)

 

The router was a new egg refurb, I think they'll exhanges but not refund. I've got to call them

So here is an idea, borrow a router and see if that changes the relationship. I hear if you go buy one at best buy or walmart you might even be able to return it

So here is an idea, borrow a router and see if that changes the relationship. I hear if you go buy one at best buy or walmart you might even be able to return it

 

smart ass

 

 

 

Now, this only happens with the new asus modem plugged in, if I plug the modem into my cheap medialink router everything works fine.

 

 

so the modem reboots but the new router is stable correct? This shouldn't matter but just for laughs try spoofing the mac address from the old router into the new router. most routers have that ability, if that don't work the new device could be bad right out of the box

so the modem reboots but the new router is stable correct? This shouldn't matter but just for laughs try spoofing the mac address from the old router into the new router. most routers have that ability, if that don't work the new device could be bad right out of the box

 

yes, the actual wireless connection to the router never goes away, it's the internet cable modem that kicks off and reboots.

If you haven't done so already you may want to double check if you are on the latest firmware. Asus is kinda known for buggy firmware despite having great routers.....when they work.

 

Update: Sorry misread your issue is with the modem.

I’d try spoofing your old mac address as a test, you have nothing to lose.  If the modem works OK with the old router and then it don’t something in the new router.  Also try bLxZe suggestion and update the firmware, not that you want to do it but if you brick the new router you could always return it and tell them it was DOA

all firmware up to date

 

 

Here are the router logs:

 

texNov 28 00:55:30 watchdog: start ddns.

Nov 28 00:55:30 rc_service: watchdog 367:notify_rc start_ddns

Nov 28 00:55:30 rc_service: waitting "restart_wan_if 0" via wanduck ...

Nov 28 00:55:32 openvpn[803]: OpenVPN 2.3.4 mipsel-unknown-linux-gnu [sSL (OpenSSL)] [LZO] [EPOLL] [MH] [iPv6] built on Nov 20 2014

Nov 28 00:55:32 openvpn[803]: library versions: OpenSSL 1.0.0o 15 Oct 2014, LZO 2.08

Nov 28 00:55:32 openvpn[803]: Diffie-Hellman initialized with 512 bit key

Nov 28 00:55:32 openvpn[803]: Socket Buffers: R=[118784->131072] S=[118784->131072]

Nov 28 00:55:32 openvpn[803]: TUN/TAP device tun21 opened

Nov 28 00:55:32 openvpn[803]: TUN/TAP TX queue length set to 100

Nov 28 00:55:32 openvpn[803]: do_ifconfig, tt->ipv6=0, tt->did_ifconfig_ipv6_setup=0

Nov 28 00:55:32 openvpn[803]: /usr/sbin/ip link set dev tun21 up mtu 1500

Nov 28 00:55:32 openvpn[803]: /usr/sbin/ip addr add dev tun21 local 10.8.0.1 peer 10.8.0.2

Nov 28 00:55:32 openvpn[803]: /usr/sbin/ip route add 10.8.0.0/24 via 10.8.0.2

Nov 28 00:55:32 openvpn[810]: UDPv4 link local (bound): [undef]

Nov 28 00:55:32 openvpn[810]: UDPv4 link remote: [undef]

Nov 28 00:55:32 openvpn[810]: MULTI: multi_init called, r=256 v=256

Nov 28 00:55:32 openvpn[810]: IFCONFIG POOL: base=10.8.0.4 size=62, ipv6=0

Nov 28 00:55:32 openvpn[810]: Initialization Sequence Completed

Nov 28 00:55:32 ddns update: ez-ipupdate: starting...

Nov 28 00:55:39 WAN Connection: Ethernet link down.

 

 

 

modem logs

 

Cable Modem Reboot due to power reset ;CM-MAC=38:6b:bb:15:a6:5b;CMTS-MAC=00:01:5c:6c:72:49;CM-QOS=1.1;CM-VER=3.0;

 

No Ranging Response received - T3 time-out;CM-MAC=38:6b:bb:15:a6:5b;CMTS-MAC=00:01:5c:6c:72:49;CM-QOS=1.1;CM-VER=3.0;

 

MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=38:6b:bb:15:a6:5b;CMTS-MAC=00:01:5c:6c:72:49;CM-QOS=1.1;CM-VER=3.0;

 

modem logs

 

Cable Modem Reboot due to power reset ;CM-MAC=38:6b:bb:15:a6:5b;CMTS-MAC=00:01:5c:6c:72:49;CM-QOS=1.1;CM-VER=3.0;

 

No Ranging Response received - T3 time-out;CM-MAC=38:6b:bb:15:a6:5b;CMTS-MAC=00:01:5c:6c:72:49;CM-QOS=1.1;CM-VER=3.0;

 

MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=38:6b:bb:15:a6:5b;CMTS-MAC=00:01:5c:6c:72:49;CM-QOS=1.1;CM-VER=3.0;

if you have the Asus NT-66 plugged it looks like the modem *may* still may be seeing the Motorola, that first mac address in the log its for Motorola

 

386BBB Motorola Mobility, Inc.

 

http://www.coffer.com/mac_find/

 

Do you have internet access with the new modem, or just a wireless connection? I'd still try spoofing the mac into the new router or resetting the modem to recognize the new mac

I have a net gear router you can borrow if you want. Lemme know.

if you have the Asus NT-66 plugged it looks like the modem *may* still may be seeing the Motorola, that first mac address in the log its for Motorola

 

386BBB Motorola Mobility, Inc.

 

http://www.coffer.com/mac_find/

 

Do you have internet access with the new modem, or just a wireless connection? I'd still try spoofing the mac into the new router or resetting the modem to recognize the new mac

 

 

The modem is a Motoralla.

 

old router = MediaLink

new router = Asus

 

I just copied and pasted what I saw, i've been flipping back between the medialink router and asus just so I have internet access in between troubleshooting. 

I see, so it picked up the correct mac of the device that was connected.  I wish I could be of more help. Just to clarify "spoofing the mac" is probably named “MAC Address Clone” or something similar, it may be worth a shot in this case. That said if the modem is rebooting with the new router connected that don't sound good regardless of what the case is.

 

 

 

EDIT:

so much for what is named, looks like Asus calls it "Special Requirement from ISP", got it from another Asus router manual.  if you want to spoof the mac with your old router's mac of 38:6b:bb:15:a6:5b  see if the path below will get you there..

 

Go to Advanced Setting > WAN > Internet Connection tab, then scroll down to the section labeled Special Requirement from ISP and enter your old mac address

When you set up the modem the first time was it a big pain to do. If it isn't that hard try and do a factory reset on the modem see if there was some kind of security on the modem allowing it to only hook to one router

Do you still have the old router? Plug it back in and compare the modem logs. Nothing obvious in the modem logs but it's curious that OpenVPN is starting on the router. Are you configuring s VPN?

I'll try to compare logs, at this point I'm ready to buy an airport extreme or something easy plug and play.

Airport Extremes aren't easy plug and play... well..... they are if you're not worried about security in any way.

 

What's your budget, Alec?  Let's talk - I'm close by enough to come help you out.

Based on the length of the thread here - http://forums.comcast.com/t5/Home-Networking-Router-WiFi/Having-issues-with-your-Motorola-SB6121-Please-post-here/td-p/1365553/page/14 - I guess there won't be an easy fix for this :-(

P.S. I love Asus routers and have one myself (an older RT-N16 model), and if tasked with choosing the weakest link between Asus and Motorola communication devices I'd personally consider Motorola to be the one causing troubles. I see that your issue only shows up when you hook the modem up with a new router... so, I'd follow the sequence:

 

1) Switch on the modem alone, not hooked up to anything at all with everything else physically unplugged and switched off - I guess there are LEDs on it to understand if it goes to restart. Make sure everything works fine

2) Hook the modem up with the old router, see if all works fine

3) Leave the modem with an old router, but switch on a new Asus router and put nearby (I have an absolutely crazy idea that Wi-Fi from Asus might somehow impact the signal level in coax cables...). Make sure if it works.

4) Hook the modem up with the new Asus router and leave router off. Make sure modem works properly.

5) Switch on the router and do factory reset. Observe what is happening with the modem...

 

As many have noted already, make sure your Motorola has the latest firmware - lots of issues often disappear with newer firmwares being installed ...

Airport Extremes aren't easy plug and play... well..... they are if you're not worried about security in any way.

 

What's your budget, Alec? Let's talk - I'm close by enough to come help you out.

What's wrong with the apple airport security ?

It's not that it's easy to setup - I've setup apple airport express/extremes... they require a utility to configure instead of just going to a website. That's to configure it properly with security, etc.

Following the following steps:

1) plug back in old router

2) verify internet connectivity and Public IP address assigned to old router's WAN

3) tell old router to RELEASE its Public IP

4) disconnect old router

5) connect new router

6) verify Public IP address (should be in the same subnet as the previous one, but not necessarily the same address.)

7) verify internet connectivity.

 

That should solve your problem.

Short term fix, daisy chain them.

A few questions:

 

Have you tried another power supply for the cable modem?

What firmware and version are you running on the NT66?

Does the modem start dropping immediately upon hooking up to new router?

Your ISP may be holding the old modem or router's MAC address...

Your ISP may be holding the old modem or router's MAC address...

 

 

Following the following steps:

1) plug back in old router

2) verify internet connectivity and Public IP address assigned to old router's WAN

3) tell old router to RELEASE its Public IP

4) disconnect old router

5) connect new router

6) verify Public IP address (should be in the same subnet as the previous one, but not necessarily the same address.)

7) verify internet connectivity.

 

That should solve your problem.

Yep that’s why I suggested spoofing the old mac address. Sota is right but for whatever reason it may be a little harder that than that to break the dhcp lease,  at least in my experience. I run dd-wrt and every couple of months I’ll toggle between routers to test latest firmware builds.  On a few occasions in the past I couldn’t reconnect I and I had call tech support to get them to break the lease. Since that experience now I just spoof the mac and could toggle between routers with no problems

...On a completely side note, if this is really a problem with a defective 6121, you can't repair or replace it and you are on Comcast, Newegg has a nice promo for a Zyxel Comcast Docsis 3.0 compatible modem for $20 after rebate - http://www.fatwallet.com/forums/hot-deals/1409307/

If it were dhcp-related then wouldn't the new router fail to get an ip on the WAN link?

Resetting the modem should take care of wiping the router's MAC address from the modem's config file. The new router might not be sending its MAC to the modem though. BTW, spoofing the modem's MAC is not necessary.

 

Power off the modem and router.

Power on modem and wait 5 minutes.

Power on router.

Test connection.

 

Just for clarification, you're using the same old modem, not a new one, correct?  If it's a new modem you need to call your ISP and give them the MAC for the new modem. Also, it may be coincidence, but from your log you posted it appears your power supply for the modem may be on its last legs. Try another power supply for the cable modem.  So, I would try a hard modem reset and also a new power supply for the modem.