[SOLVED] Internet connectivity issues....stumped

[drjones]

I've got a client on Comcast Bus. Class internet with comcast VOIP phones and their internet has been dropping every couple weeks.

The problems started when they moved into a new office and made the switch to Comcast. Before they were on Surewest & it was rock-solid.

Soon as they move into this new office, the internet keeps dropping about every 2/3 weeks or so. A power cycle of the comcast modem resolves the issue. The Sonicwall is the same they've had for years.

The last time it happened earlier this week, I said the hell with it & had Comcast replace the modem. Now the issue is significantly worse & keeps cutting out every few hours.

Comcast is insistent there is nothing wrong on their end and also said that if it truly was their connection dropping, the clients VOIP phones would stop working too.

I'm trying to rule out any problems on the LAN. We did not make any configuration changes to the server that I'm aware of - they've been running exchange for a while.

Here's their network setup:

- Comcast modem plugs into a Sonicwall TZ100.

- They have Cisco phone boxes and a Cisco managed switch.

- SBS 2011, DC running Exchange and file/print sharing. It handles DHCP.


Here's what I've tried/checked:

- Comcast replaced modem, problem got worse.

- Firewall OFF on Comcast modem.

- DHCP Disabled on Sonicwall: Check.

- DHCP disabled on Netgear router/WAP: Check.

- DHCP disabled on NAS: check. (They have a Netgear NAS for backup that can distribute DHCP)

- DHCP IS enabled on the Comcast, but different scope. Their LAN is 10.10.0.X and the Comcast is 10.1.10.X. I believe Comcast does not recommend disabling DHCP on their modems, but I'm thinking of changing it to 192.168.16.X

- Replaced Cat6 cable running from modem into Sonicwall WAN port with a new Cat6 cable.

- Checked & traced all physical cables, ensured all cables look good/healthy & are fully seated.

- Checked that all power adapters are fully seated in wall & devices - the modem power is a large wall wart that is connected upside-down - doesn't seem super stable.

However the cord that is currently installed & connected to the modem is zip-tied together with the power to the phone box - is it possible the power supply is bad & the comcast guy re-used the same one with the second modem?


I looked in the event logs on the DC & found the following:

Event 1050, DHCP Server - the DHCP/BINL service on the local machine encountered a network error. The error was: 0x2

Warning 1056 "the DHCP service has detected that it is running on a DC and has no credentials configured for use with Dynamic DNS registrations initiated by the DHCP service."

WINS Errors 4224 and 4291

Could any of those errors be causing the problem?

It just seems strange that this all started with the new office/new internet and also became WORSE after a new modem was installed....should we go third times the charm & have comcast replace the modem yet again??

 

[SAG]

Had a client move into a bigger place across the street. Moved their Comcast and stuff. Same thing happened. Every week or two the internet would go to pot. Bounce the Comcast gateway and all was good. Two gateways later and I agreed with Comcast that it likely isn't their hardware. Had almost given up.... almost.

Customer needed a small UPS for the X-Ray station and said he'd pick it up. He's fairly technically inclined so I said "sure". A few days later he called me in. He had picked up two of them because of some "special" they were running. Thought about keeping the other as a backup. I suggested we use it for their network equipment in case of a power blip. Office uses all laptops except for the X-Ray station so this would be ideal. Put it in, never had the problem since. My assumption is that the power in that building was either dirty, or someone in another suite was using something that would draw too much at any given time causing an issue with the Comcast. I always meant to go back to using the power directly from the wall to see if the internet dropping issue came back. But he hated that office and moved out after his year lease was up anyway.

 

[drjones]

Had a client move into a bigger place across the street. Moved their Comcast and stuff. Same thing happened. Every week or two the internet would go to pot. Bounce the Comcast gateway and all was good. Two gateways later and I agreed with Comcast that it likely isn't their hardware. Had almost given up.... almost.

Customer needed a small UPS for the X-Ray station and said he'd pick it up. He's fairly technically inclined so I said "sure". A few days later he called me in. He had picked up two of them because of some "special" they were running. Thought about keeping the other as a backup. I suggested we use it for their network equipment in case of a power blip. Office uses all laptops except for the X-Ray station so this would be ideal. Put it in, never had the problem since. My assumption is that the power in that building was either dirty, or someone in another suite was using something that would draw too much at any given time causing an issue with the Comcast. I always meant to go back to using the power directly from the wall to see if the internet dropping issue came back. But he hated that office and moved out after his year lease was up anyway.

Hmmmmph........as I noted above, the power supply for the modem is connected directly to the wall.....I've seen routers brand-new out of the box not function properly if you don't use the proper power adapter, so I know what you're saying about power issues.....

They need a new APC anyway....I'm going to go there today & connect the comcast directly to the APC or a surge protector & see if that helps.

Will definitely plug it into the new APC when that arrives too.....

 

[angry_geek]

Had one case similar. Turned out to be a bad ups. Yup, take a line voltage tester with you and see if you're getting voltage fluctuations.

 

[drjones]

Funny you guys should mention this....they currently have an APC SmartUPS 1500....I replaced the battery about a year ago, all of a sudden yesterday the red light is on & says battery needs replacing again.

I do believe we are looking at bad power....the question is, what do we do to fix this? I don't want them to start chewing through UPS's.....assuming this is indeed the problem.

I'm gonna swing by & connect the Comcast modem to a surge protector see if that helps.

 

[brandonkick]

Funny you guys should mention this....they currently have an APC SmartUPS 1500....I replaced the battery about a year ago, all of a sudden yesterday the red light is on & says battery needs replacing again.

I do believe we are looking at bad power....the question is, what do we do to fix this? I don't want them to start chewing through UPS's.....assuming this is indeed the problem.

I'm gonna swing by & connect the Comcast modem to a surge protector see if that helps.

That's not going to fix your problem.

You most likely need an electrician.

 

[drjones]

That's not going to fix your problem.

You most likely need an electrician.

I'm going to connect it to a surge that is on a different wall, hopefully a whole different circuit.

Should hopefully at least help narrow down the problem - if it's at all stable (or even worse) then that shows us the issue. Right?

If moving the power connection helps/solves it, then we'll call an electrician.

 

[altrenda]

Do I have this right?
Same customer equipment, except new location and provider, new modem
Connection drops every 10 days or so, power cycling modem brings it back.
Comcast replaces modem and problem gets worse.

Could be a power line problem, but my experience with cable company equipment is that a large percentage of it is refurbished and has problems. (at least with Time Warner and Charter, not much Comcast in my area.)

No matter what the Comcast remote line test says, I would replace the modem again, while checking out the powerline quality.

Note: I see the OP asked the same question :Also, when they changed the modem did they change the power supply as well, or reuse the old one?

 

[SilverLeaf]

Don't rule out poor cable terminations if the incoming line is coax. Some of those "quick install" coax terminations can fail to make adequate contact with the braided shield, and can cause all sorts of funky, intermittent issues.

 

[drjones]

Do I have this right?
Same customer equipment, except new location and provider, new modem
Connection drops every 10 days or so, power cycling modem brings it back.
Comcast replaces modem and problem gets worse.

Could be a power line problem, but my experience with cable company equipment is that a large percentage of it is refurbished and have problems. (at least with Time Warner and Charter, not much Comcast in my area.)

No matter what the Comcast remote line test says, I would replace the modem again, while checking out the powerline quality. Also, when they changed the modem did they change the power supply as well, or reuse the old one?

Yes except the Cisco phone system/switch is new, but again - all we have to do to get it working is power cycle the modem AND the phones are constantly working without interruption.

I'll try the new power source and then will have comcast go round three with the modem...sheesh...

And no idea if he changed the power supply...I think he may have re-used the old one because of the way it's zip-tied to other cables. Pretty sure he DID re-use the old one.

The second comcast tech actually left a brand-new shrink-wrapped modem there; I'll grab that power supply & use it.

 

[drjones]

Ok, they're a contractor so they called one of their electricians to check the power - it's all clear.

We're starting to suspect the Sonicwall.

I moved the Comcast power connection to a whole separate outlet, no difference.

 

[brandonkick]

I'm going to connect it to a surge that is on a different wall, hopefully a whole different circuit.

Should hopefully at least help narrow down the problem - if it's at all stable (or even worse) then that shows us the issue. Right?

If moving the power connection helps/solves it, then we'll call an electrician.

I was under the impression that the only thing you were going to do was add a surge protector to the mix. This alone would do diddly squat. Moving to a new outlet (if indeed it was on a different circuit) could help improve the situation.

There is no reason to not suspect the sonic wall, except that it worked fine before. Connect directly to the modem if you can and see if the problems disappear.... this may be difficult but your either going to need to eliminate or replace the sonicwall to find out if it's causing the issue or not.

Could it be an issue of the sonicwall not being set up correctly for the new connection? I have no experience with those type of devices.

 

[drjones]

Ended up being the Comcast modem.

They swapped out the SMC with a new Netgear modem that Comcast is now installing, haven't had an internet hiccup since....(*&%#$ Comcast...