Question Switch causes network problems after reboot

gordonm

Novice Member
Hi all,

I have a house that has the following set-up:

- 7 rooms each with their own Ethernet port
- 5 PoE security cameras

The kit that serves this set-up is as follows:

1. The main router is a NETGEAR R7800 Nighthawk X4S Dual-Band AC2300
2. That router connects to a switch, a Netgear ProSafe GS516TP 16 Port Gigabit PoE.
3. The switch powers the 5 cameras which are all Y-CAM OUTOOR HD PRO's via PoE.
4. The switch also has cabling going out to service the 7 rooms
5. Because of limited wifi signal, two of the rooms have another wifi router connected via the Ethernet port - both TP-Link TL-WR841N 300 Mbps Wireless N units.

All of this works absolutely fine most of the time, but the switch seems to cause problems every so often. Basically the entire local network goes down. Disconnecting the switch resolves the problem to the extent that the router and wifi are restored. But re-connecting the switch brings it all down again.

It's as though the switch messes up all of the traffic. It's not clear to me exactly what fixes it, one time re-installing the switch firmware worked. The next I had to take all the Ethernet cables out of the switch and plug them back in one-by-one after a reboot.

The events that have coincided with the switch problems (that I know of) have been (1) disconnecting the PoE cameras one time and (2) a power cut which forced the switch off and on again.

Does anyone have any ideas as to what might cause the switch to do this? I really need it to be much more reliable.

My thoughts were PoE overload (although the 5 cameras are within the maximum of the switch) and some kind of looping problem that the switch cannot deal with after a reboot. But these are just guesses really.

Thanks.
 

Chester

Well-known Member
Welcome to the forums Gordon.

Just curious, why did you use TP-Link routers instead of just Wireless Access Points (WAPs)? I'm guessing you had them to hand.

This might not be the switch at fault at all. Try disconnecting the TP-Link routers, turn off the Netgear router and the switch, turn on the Netgear router, turn on the switch. Everything else but WiFi hanging together OK now?

That's a worthwhile test to start with because this could be all sorts of things, so it's important to go through a process of elimination. Let us know how you get on...
 

Kristian

Member
A few quick thoughts in addition to Chester's post. Make sure that the routers you are using for Wifi have DHCP disabled and anything else they're not using. The switch is managed, so has it got the latest firmware configured? Is spanning tree configured correctly (although I doubt there's any need to change the config as you only have one STP enabled switch)? Is there a chance that the APs are bridging and therefore forming a loop? Any cables mis-patched and casuing a loop?
 

Chester

Well-known Member
For most of the reasons you suggested, that's why I suggested to turn the TP-Link routers off.
 

MacrosTheBlack

Well-known Member
Look up your switches and routers on the manufacturer websites and check they are all on the latest firmware. Often fixes are released for issues like that.

Also check you haven’t got any network cables going (directly or indirectly) from the switch back into itself, as that can cause a loop back and crash the switch after a short while.
 

mickevh

Distinguished Member
Another possibility is that it's not the switch itself, but something plugged into it (for example a jabbering NIC.) The way to check that is of course to unplug everything from your "bandit" switch except the uplink to the rest of the network and wait to see if is falls apart again. Though that could be somewhat inconvenient to do.
 

gordonm

Novice Member
Thank you for all the suggestions.

A few points to clear up:

- Yes, I was using the TP Link Routers as they were kit I happened to have, and the plan was to put them into "Access Point Mode" (although see below)
- The switch does have the latest firmware
- Spanning tree - this will be set to the switch default, whatever that is. I have not altered it.
- Is there a chance that the APs are bridging and therefore forming a loop? I'm not sure how I could check for that.
- Any cables mis-patched and causing a loop? I double checked all the cabling today and nothing looks untoward.

So today I went to the house. After the problem, the switch had been disconnected so only the main wifi was working. So I (1) disconnected the two TPLink routers, (2) reconnected the switch --> All is good, (3) Reconnected the routers --> All is good. So somehow it looks as though disconnecting and then reconnecting the TPLink routers fixed matters.

I then looked at the admin panel for both the TPLink routers. It turns out both of them were in "Router mode" not "Access Point mode", so I set them up correctly. Presumably this may have meant that there were 3 DHCP servers operating. All still good on the network after this change.

So, things are fixed for the time being, but it's a bit disconcerting that the network started working even before configuring the TPLinks correctly. Only time will tell how reliable it is I suppose :)
 

Chester

Well-known Member
I’ve not played with those TP-Link routers. Do you have to ‘Save’ the configuration after you’ve adjusted the settings? Some OfficeConnect stuff is like that. If you don’t, they revert to last saved settings after a reboot.
 

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