Strange LAN Drop-Out Behavior

[prazvt]

Hi All - I'm new to SmallNetBuilder, but I've found solutions to problems posted here before. I've been having a weird issue on my home wired & wireless LAN and I can't quite pinpoint the possible cause. Please bare with me while I explain the setup first.

Our house is wired for ethernet, but because we use Dish for TV, the only cable line coming in for the cable modem is through the garage. So our main modem and router sit downstairs in the dining room (Motorola modem + Asus RT-AC66U). We have a control panel in the master bedroom closet that houses all the ethernet cables for each room. So I have a pair of Netgear XAV5101 power line adapters connecting the router downstairs to the control panel.

The output of the control panel is to a Netgear GS105E 5port gigabit switch, and 4 rooms are connected to the switch (3 bedrooms + living room downstairs).

Because of the weak wireless signal upstairs, I have an Asus RT-AC68R running in AP mode in my room. Connected to it is a Synology DS413 NAS, a PS3, a Dish DVR, and a Squeezebox Touch. Other devices connect wirelessly.

The computer room has one gaming PC connected to the wall directly, and the living room and master bedroom both have switches w/ a mix of devices connected wired.

Finally...the ISSUE:

The signal coming out of the port in my room (w/ the '68 router) fails ever so often for a few hours. None of the devices will get a LAN IP and I can't get an internet connection via the '68's wireless connection (2.4GHz G/N, 5GHz AC). But if I go to the computer room, the gaming PC will have connection. If I connect my laptop directly to the wall port in my room, it won't get an IP; it'll show a 1GBps connection, but w/ the exclamation mark.

In this morning's incident, nothing was working until I turned on the gaming PC in the computer room. Now suddenly the signal coming out of the port in my room is fine and wireless is fine. Kind of bizarre...

From what I can tell (and I could be wrong), the root cause could be:

- The GS105E switch connecting the rooms is going bad?
- Issue w/ the power line adapters?
- Physical cable issue?
- Other 'networking' issue I'm not aware of?

I think both the routers are OK. The fact that only my room is affected makes me think it's something from the power line adapters onward.

Apologies for the LOOONG explanation. But I really would appreciate anyone's help here

Thanks,

Prashant

 

[thiggins]

A diagram would help a lot.

How are the two routers connected? How are the machines in the "Computer Room" connected?

 

[prazvt]

A diagram would help a lot.

How are the two routers connected? How are the machines in the "Computer Room" connected?

Hi thiggins - I've attached a quick diagram to illustrate the major connections.

The downstairs RT AC66U is connected directly the cable modem; it outputs to a power line adapter.

The upstairs power line adapter feeds the GS105E switch, which feeds the network connection to the various rooms.

The upstairs RT AC68R is in AP mode and is connected to the wall ethernet outlet via one of the client ports on the AC68R.

Master bedroom computers (2) are connected via a switch that is connected to the ethernet port in the master bedroom.

Computer room computer is connected directly to the wall ethernet outlet.

 

[thiggins]

Thanks for the diagram. The problem isn't the powerline adapters. If they were bad, nothing would be connected to the internet.

Your problem could be:
- bad /loose connection at the wall jack in your room
- bad port on the GS105E switch

Have you considered putting the powerline adapters between the cable modem and RT-AC66U WAN port and moving the router upstairs? This has nothing to do with your problem. Just would let the RT-AC66U's ports be better used and possibly give you better wireless upstairs.

 

[prazvt]

Thanks for the diagram. The problem isn't the powerline adapters. If they were bad, nothing would be connected to the internet.

Your problem could be:
- bad /loose connection at the wall jack in your room
- bad port on the GS105E switch

Have you considered putting the powerline adapters between the cable modem and RT-AC66U WAN port and moving the router upstairs? This has nothing to do with your problem. Just would let the RT-AC66U's ports be better used and possibly give you better wireless upstairs.

Thanks for the input. For now, I've switched out the GS105E with another one and updated the firmware on that one as well. I'll see if this occurs again and if it does, I'll check the wall jack next.

As for your suggestion - actually for a couple of years, the setup was pretty much like that. But the network control panel is in one of the walk-in closets in the master bedroom, so the wifi signal ends up being useless for most of the upstairs. The other reason I ended up putting a router downstairs is because the main phone line comes in through the garage and so the Vonage box has to be there. That is the other device connected to the RT-AC66U (sorry forgot about that when I was drawing the diagram).

 

[prazvt]

UPDATE: I found that the terminations for 3 rooms weren't 100% correct. In other words, 1 or 2 pairs of connections were shown as problematic when I connected the LAN tester. So I reterminated the family room, master bedroom and my room and verified everything with the LAN tester.

Now it gets a little weird. I connected the newly terminated cables back to the switch and got nothing from master bedroom and my room connection-wise. But when I connected a laptop directly to the cable coming from downstairs, it was getting internet.

So I said ok...let me check the computer room machine; went in there and it was already on, but apparently frozen. I forced a hard shutdown and when the machine booted up it had Internet. Went back to the master bedroom and my room and internet & LAN were back up again. This is the 2nd time I've noticed the LAN going back to normal when the computer room machine was powered on (normally).

Is there any reason why that machine would impact the home LAN? It's simply connected via ethernet and has a static ip that's assigned by the router. It could just be a coincidence, but just wanted to rule anything exotic out that I am not aware of.

I will, of course, check the termination w/ the LAN tester tomorrow.

 

[Dreamslacker]

Is there any reason why that machine would impact the home LAN? It's simply connected via ethernet and has a static ip that's assigned by the router. It could just be a coincidence, but just wanted to rule anything exotic out that I am not aware of.

I will, of course, check the termination w/ the LAN tester tomorrow.

Check the machine for malware. I've encountered this situation before when my computer-idiot of a sister managed to get rather exotic malware on her system. It overloaded the switch with broadcast packets and the switch went into limbo. Unplugging her computer restored network (and internet) access to the rest of the computers.

It is also possible that you had a piece of software that was stuck in a broadcast loop (or was in such a mode when the computer glitch occurred).

 

[prazvt]

Check the machine for malware. I've encountered this situation before when my computer-idiot of a sister managed to get rather exotic malware on her system. It overloaded the switch with broadcast packets and the switch went into limbo. Unplugging her computer restored network (and internet) access to the rest of the computers.

It is also possible that you had a piece of software that was stuck in a broadcast loop (or was in such a mode when the computer glitch occurred).

I suspect it was probably the latter; I just reformatted and re-installed Windows 8.1 the other day, so I doubt there's malware on the machine yet (only thing I've installed are drivers, a game, and Office 2013). The printer is shared on the network through that computer and my dad was trying to print over the LAN from one of his Windows 2008 R2 machines. It was getting a network error until I rebooted his machine. Anyway, will monitor things and double check my machine for any malware.

Thanks for the input!

 

[AndyFlysTrikes]

Im guessing the powerline gear (Neatgear 500mbps series) has old firmware that has the "Green" Sleep problem whereby when there is no activity it puts itself into a low power use state.....but can't then get out of it.

I had the same gear with a single port device one end and the prioritised 4 port device at the other end. When the firmware was updated to latest and greatest which in the netgear forums was specifically identified as tossing out the whole power save functionality my problems disappeared.

The way to prove or disprove is to cycle power to both powerline devices and see if the problem immediately disappears once the devices have booted and are operating ....

If you look here http://forum1.netgear.com/forumdisplay.php?f=54 you'll see that the problems aren't unique (in fact the post I was looking for is this one http://forum1.netgear.com/showpost.php?p=443489&postcount=26 )

Andy

 

[Dreamslacker]

@andyflystrikes: Good point there. Never considered that factor since I only ever worked with TP-Link & Aztech powerline modules that don't have that problem.