Observer

(SBG6580) Can't ping other desktop at 192.168.0.2 though connects perfectly otherwise??

I have just bought a Motorola/Arris Surfboard SBG6580 to replace an identical rented one. Everything is perfect, and everything works the same, but one thing. When on one wired desktop, I connect to another wired desktop at 192.168.0.2. Works great; can read and copy files. But ping 192.168.0.2 fails. I can ping 192.168.0.1 and 192.168.0.3 and google.com but not 192.168.0.2 (when 0.2 is the other desktop). I believe it's resolving okay because if I ping the Host Name (that appears under DHCP clients when logged in to modem)
ping bob-pc
it says Pinging bob-pc [192.168.0.2] with 32 bytes of data
but always fails.

I did the software reset on modem but not the back "button." Repowered everything. Firewall is OFF and both desktops' firewall is OFF.

These show on the new modem
Hardware Version 1
Software Version SBG6580-6.5.2.0-GA-06-077-NOSH

There are several items in the event log; I don't know if they are meaningful.

Again, this worked on the rented SBG6580 but not the one I replaced it with. And a drive is shared on the connection; just can't PING.

9 REPLIES
Observer

Re: (SBG6580) Can't ping other desktop at 192.168.0.2 though connects perfectly otherwise??

What I wonder about is that I read that TWC-supplied modems use firmware
SBG6580-3.5.8.2-GA-01-488-01-NOSH
but when you buy the very same modem, they push
SBG6580-6.5.2.0-GA-06-077-NOSH

on you. Unfortunately I did not write the firmware version down before returning the rental so I'm not sure if the first number was what I was on, but if so, might that explain it? That seems to be the only thing different.

Expert

Re: (SBG6580) Can't ping other desktop at 192.168.0.2 though connects perfectly otherwise??

Set the dhcp start to 192.168.0.100

 single last digits are trouble with some devices.

 that's also an obsolete device and don't expect it to work much longer, It may not be the IPv6 compatable one either. All in ones are not recomended and for what you're trying to do, you need a seperate router.

 

Observer

Re: (SBG6580) Can't ping other desktop at 192.168.0.2 though connects perfectly otherwise??

Thank you for the 100+ addressing suggestion, but it didn't change the result. I will admit that I'm surprised that single last digits would be an issue in this decade.

 

Let's say SBG6580s are being phased out in favor of a newer model. I can't imagine how I'd benefit, unless for some reason I went to multi-hundred meg rates (but I'm screaming fast at 100 for everything I do). So I'll get the same 100M speed. There will be AC wireless speed but I don't stream so that doesn't do anything. Bottom line, I've done exactly what I'm doing for years with a combo modem - this very model in fact. I can see that that you're a major critic of combo modems, and of anything over 2 years old, and especially the SBG6580. But except for perhaps some exotic usage, it's dead perfect for me - except for this strange new issue.

 

With the 6580, ipconfig -all shows a link-local IPv6 address; I don't know how Spectrum implements it. Yet I might be using IPv6 in a few years, so I'll try to be careful to concentrate on the capability if I do. Thanks for focusing me on that.

 

Thank you for your opinion.

Observer

Re: (SBG6580) Can't ping other desktop at 192.168.0.2 though connects perfectly otherwise??

FWIW, Machine A can ping machine A, and can ping an Android phone wirelessly connected to the modem/router. Machine B can ping machine B, and can ping the Android. But B can't ping A, and vice versa.  This is all so odd because the identical model modem did that perfectly while on the modem lease, but when I swapped and became "user's modem," the PING deficiency appeared.  In the modem, at least this "new" modem, firewall is off, and everything except WAN blocking is checked on "Advanced" and no filtering or forwarding or triggers - so it's a mystery.

Established Sharer

Re: (SBG6580) Can't ping other desktop at 192.168.0.2 though connects perfectly otherwise??

Instead of referring to "Android Phone," "Machine A," and "Machine B", show us the IP addresses being assigned to each device.  The built-in router is normally going to be assigned 192.168.0.1.  If you leave DHCP on its default starting point 192.168.0.1, the first device to log in gets 192.168.0.2, the next one will be given 192.168.0.3, etc.  Some Apple IOS devices still don't like to see the last octet be a single decimal digit; it generates an "Invalid Class" internal network error.

If you have any devices with static (fixed) IP assignments, the DHCP has to start ABOVE the highest static address you have assigned.  Remember to account for wireless printers, video cameras and servers, doorbells, thermostats, other wireless access points, etc. if you are managing your own static IPs. 

Observer

Re: (SBG6580) Can't ping other desktop at 192.168.0.2 though connects perfectly otherwise??

Sorry, I thought you'd pick up the relevant info from earlier in the thread.
0.2 is Machine A. 0.3 is B. 0.4 is Android.
A Can ping itself and Android.
B Can ping itself and Android.
A can't ping B. B can't ping A. Those are desktops.

BTW they're now sitting at .100, .101 and .102 after the experiment suggested a couple of posts ago. I couldn't make them return to .2, .3, .4 after telling DHCP to start from 0.2 and deleting the clients and booting modem. I'm about to restart both desktops now to see if that does it.

Established Sharer

Re: (SBG6580) Can't ping other desktop at 192.168.0.2 though connects perfectly otherwise??

The first 'rule' for home users is to NEVER clone the same MAC address into more than one device on your home network.  If you did that, it's time to press the factory reset button on each box and hold it in for five to ten seconds or until you see the LED indicators doing something different from a normal power-on restart. 

 

The next 'rule' is to restart all devices after changing the DHCP IP address plan.  Then 'repair' the connections of each device that complains about a failed network connection or duplicate IP address.   Different versions of Windows (7, 8.0, 8.1, or 10) or other OSs each respond with slightly different warning messages. 

 

Any time you connect a different modem [or in your case a combination gateway unit] to Spectrum's cable network, you MUST perform a full  factory reset on the MODEM (not your router) as described in the first paragraph.  This re-registers your device on the cable modem server and should force a reload or update of the boot file.  Many modems will not actually reset unless you disconnect the cable.   After this step is complete, THEN you restart your router and each connected device.  

 

Last, some OSs and some routers don't allow a device to ping its own assigned IP address.  Many network servers are also programmed to ignore frequent or repetitive ping requests, especially when they are busy processing real network traffic.  

Observer

Re: (SBG6580) Can't ping other desktop at 192.168.0.2 though connects perfectly otherwise??

Thanks for those ideas, but none of those apply here or solve this mystery. BTW there's no address conflict; certainly not MAC addresses, and not IP addresses. The modem/router sequentially hands them out to DHCP client requesters starting at the lowest number (192.168.0.2 here), and isn't handing out the same one twice. I think I covered that in my reply to your previous post.

To summarize for anyone picking up the thread, the original issue remains: I returned an SBG6580 modem and bought an identical SBG6580 modem. I registered w/ ISP and continued having Internet. But before, on the lease, one desktop (at 192.168.0.2) could PING the other desktop (at 192.168.0.3); yet now, with the bought unit, PING fails. (Both are plugged into the cable modem/router)

Expert

Re: (SBG6580) Can't ping other desktop at 192.168.0.2 though connects perfectly otherwise??

I would not use those single last digit addresses, especially if there's any apple devices.

start dhcp at 192.168.x.100

 Next issue is to turn off IPv6, some of the 6580's didn't support it properly. there were v0, v1, v2

You may also have an antivirus issue in a machine, Whatcha running McCaffee?

And I sure as heck wouldn't use an all in one combo.