Network Keeps Dropping off

[dipsylalapo Supervisor]

Hey everyone, 

 

I haven't touched my network setup in a long time as it's been working with no issues for months. 

 

Over the last week or so, I've noticed that some devices struggle to stay connected to the network. At the moment, there's a Kindle and a desktop that are struggling to stay connected. 

 

I've no idea where to start looking into this so any pointers would be great!

 

I have a USG, two Unifi APs (Lite) and a D-Link switch (DGS-1100-08P).

[Mindovermaster Moderator]

These are wireless devices, (computers) I'm guessing? Could be your APs failing. Or somehow losing power. How old are the unifi APs?

 

Wait for Budman for further instructions. 😛 

[dipsylalapo Supervisor]

3 minutes ago, Mindovermaster said:

These are wireless devices, (computers) I'm guessing? Could be your APs failing. Or somehow losing power. How old are the unifi APs?

 

Wait for Budman for further instructions. 😛 

Yeah all wireless devices. Just over a 12 months old so I really hope not!

[adrynalyne]

11 minutes ago, Mindovermaster said:

These are wireless devices, (computers) I'm guessing? Could be your APs failing. Or somehow losing power. How old are the unifi APs?

 

Wait for Budman for further instructions. 😛 

Multiple APs failing?🤨

@dipsylalapo

Start here: look at the events and alerts in the Unifi controller for clues. When is the last time you restarted your network equipment?
 

 

[dipsylalapo Supervisor]

2 minutes ago, adrynalyne said:

Multiple APs failing?🤨

@dipsylalapo

Start here: look at the events and alerts in the Unifi controller for clues. When is the last time you restarted your network equipment?
 

 

Just this morning, there was an update that was pushed. I don't think they two are connected as the timings don't match up.

 

Nothing specific in the alerts.

[dipsylalapo Supervisor]

So I think I've resolved it. I did some Googling and changed the DTIM period from 1 to 3. Not something that I'd changed or has been a problem before, but it seems to have resolved the issue.

 

The 18 or so devices that I have connected seem to be holding steady. Something that hasn't happened all day. 

 

Bizarre.

 

Edit - @BudManPlease stand down 😉

[Mindovermaster Moderator]

Glad you got it sorted, bro!  

[+BudMan MVC]

That makes no sense.. Changing the mode from 1 to 3 would allow devices to say sleep longer.. 3 allows for longer time period before multicast/broadcast traffic is sent..  And when the client should wake up so to speak and look for multicast traffic.. But can be problematic for batter life if they stay away for the longer period until the next beacon, etc..  Do you have a lot of multicast/broadcast traffic on the network?

 

This could be a red herring sort of "fix".. And the devices that are having the issues are non apple devices?

 

I would leave it at 3 for a few days, and then try setting it back to 1 - does the issue come back?

 

So the issue is they drop off, when their lease expires?  Since they can not get a new IP?  That could be related to why an increase in the dtim helped.. But points more to a problem with your dhcp server..

 

If you put it back, and see the problem - I would check to see what the lease time is, when client gets lease - and then when does it drop off?

[adrynalyne]

1 hour ago, BudMan said:

That makes no sense.. Changing the mode from 1 to 3 would allow devices to say sleep longer.. 3 allows for longer time period before multicast/broadcast traffic is sent..  And when the client should wake up so to speak and look for multicast traffic.. But can be problematic for batter life if they stay away for the longer period until the next beacon, etc..  Do you have a lot of multicast/broadcast traffic on the network?

 

This could be a red herring sort of "fix".. And the devices that are having the issues are non apple devices?

 

I would leave it at 3 for a few days, and then try setting it back to 1 - does the issue come back?

 

So the issue is they drop off, when their lease expires?  Since they can not get a new IP?  That could be related to why an increase in the dtim helped.. But points more to a problem with your dhcp server..

 

If you put it back, and see the problem - I would check to see what the lease time is, when client gets lease - and then when does it drop off?

I bet he triggered a re-provision with the setting change  and that was what fixed whatever weird state the APs were in. 

[+BudMan MVC]

Quite possible sure..  It seems odd that changing dtim would have such an issue to be honest.. My guess is something to do with dhcp.. That could possibly be related..   Loss of lease would for sure drop a client off the network.

[dipsylalapo Supervisor]

On 5/9/2020 at 10:37 PM, BudMan said:

That makes no sense.. Changing the mode from 1 to 3 would allow devices to say sleep longer.. 3 allows for longer time period before multicast/broadcast traffic is sent..  And when the client should wake up so to speak and look for multicast traffic.. But can be problematic for batter life if they stay away for the longer period until the next beacon, etc..  Do you have a lot of multicast/broadcast traffic on the network?

 

This could be a red herring sort of "fix".. And the devices that are having the issues are non apple devices?

 

I would leave it at 3 for a few days, and then try setting it back to 1 - does the issue come back?

 

So the issue is they drop off, when their lease expires?  Since they can not get a new IP?  That could be related to why an increase in the dtim helped.. But points more to a problem with your dhcp server..

 

If you put it back, and see the problem - I would check to see what the lease time is, when client gets lease - and then when does it drop off?

Of course you were right  Sorry missed these last few posts. The issue is back today. 

 

One of the devices (an iPad mini) still has the issue but another iOS device has joined the fray with random disconnects. 

 

I've set the DTIM back to 1 and I'll see what happens. Do you need to know the bits re. the DHCP now or after they have issues?

 

EDIT - So the iPad Mini is still not connecting. It has an IP on the lease table, due to expire 24 hours from now.

[dipsylalapo Supervisor]

So just an update on this it. The drop off seem to happen around the time the DHCP lease expires. It seems to take a few attempts or longer for it get an IP. 

[+BudMan MVC]

Yeah that would make more sense.. Whats your dhcp server - some ###### router?

 

To be honest 3 vs 1 on dtim would prob make that worse..  How exactly are you setup?  What is the layout of your network.. You said usg and some AP - but are the ap wired, or using wireless uplink to each other?  Never ran dhcp on the usg myself - running it at my sons place, but its only been a week or so - and to be honest just the little bit been over there setting stuff up, have seen some dhcp issues.. shrugged it off - because it worked after a bit, etc.

 

He just got a new place, and had a usgp3 on the shelf, told him he could have it - he got a flexHD for his AP.. And stuff reports to my controller so I can keep an eye on the network... But I can see getting him a pfsense box at some point..

 

I had that usg as my router for a few weeks, couldn't get rid off it fast enough if you ask me (sg4860 was on back order at the time).. While I love their AP.. And the usg is a great price point.. And has some great eye candy, etc.. Not overly impressed to be honest - the management is horrible for any sort of firewall rules, etc..

 

Wouldn't be surprised if issues with the dhcpd on it.. What firmware you running?

 

With a working dhcp as it suppose to, your lease should never get past the 50% mark, since that is when it renews.  So if you have a 24 hour lease, every 12 hours you should get a new 24 hour lease.. It should never get close to expired..   The closer it gets the more often it asks for renew.. Until finally it gives up, drops the lease and does a discover - you should never get there.  If you are, something is wrong.

 

If its doing that - then yeah you could see a disconnect from internet, and if taking a bit to get new one from discover - you could see some down time.

[dipsylalapo Supervisor]

On 5/13/2020 at 10:23 PM, BudMan said:

Yeah that would make more sense.. Whats your dhcp server - some ###### router?

 

From what I can tell that's all set to Auto/default at the moment.

Quote

To be honest 3 vs 1 on dtim would prob make that worse..  How exactly are you setup?  What is the layout of your network.. You said usg and some AP - but are the ap wired, or using wireless uplink to each other?  Never ran dhcp on the usg myself - running it at my sons place, but its only been a week or so - and to be honest just the little bit been over there setting stuff up, have seen some dhcp issues.. shrugged it off - because it worked after a bit, etc.

I have my cable modem attached to my USG  which is connected to a switch and the two APs are hardwired to this. Like below

On 5/13/2020 at 10:23 PM, BudMan said:

Wouldn't be surprised if issues with the dhcpd on it.. What firmware you running?

 

It's running 4.4.51.5287926 which is latest stable build

 

On 5/13/2020 at 10:23 PM, BudMan said:

With a working dhcp as it suppose to, your lease should never get past the 50% mark, since that is when it renews.  So if you have a 24 hour lease, every 12 hours you should get a new 24 hour lease.. It should never get close to expired..   The closer it gets the more often it asks for renew.. Until finally it gives up, drops the lease and does a discover - you should never get there.  If you are, something is wrong.

 

If its doing that - then yeah you could see a disconnect from internet, and if taking a bit to get new one from discover - you could see some down time.

Is there any way I can check/confirm this? Set a shorter lease time (say a few hours) and see what happens there?

 

On Saturday when I was looking into it a bit more I noticed that a machine we have flat out stopped connecting to the network because my wife was in the middle of something and needed to get going ASAP, I put together a new wireless network and move over the 2/3 devices that were having issues to it. Since then those devices have been fine. I'm going to do some digging today to see if I can see if there's a difference in the set up. 

 

Thanks again!

[+BudMan MVC]

On 5/18/2020 at 3:03 AM, dipsylalapo said:

Is there any way I can check/confirm this? Set a shorter lease time (say a few hours) and see what happens there?

That would be a good way to get your problem window into a shorter time frame from troubleshooting sure.

 

Do you have dhcp snooping enabled or not?  If you have it enabled have you setup the trusted dhcp server?