main_icn_My_Vodafone main_icn_Search main_icn_Chevron_right main_icn_Chevron_down main_icn_Close main_icn_Menu social-facebook social-google-plus social-linkedin social-twitter social-youtube main_icn_Community_or_Foundation main_icn_Location main_icn_Network_signal

Broadband connection

Connection issues, DHCP/DNS

andyhoe
2: Seeker

Hi all, having annoying problems with my Vodafone/Cityfibre connection. When it's working it's generally fine. If it disconnects for whatever reason then I have huge problems trying to reconnect. I just get a red flashing Internet light.

I can spend a couple of hours repeatedly rebooting everything and it might come up again, if it does I then often have DHCP/ DNS issues. I cannot get an address, but if I use a static IP and a public DNS server on my clients they will work. I suspect a router issue, even when I can connect to the router page, none of the settings usually load. Vodafone have logged a ticket with Cityfibre but I'm not convinced it's their issue 

Not sure what to try next! Any ideas?

View more options
16 REPLIES 16
CrimsonLiar
14: Advanced member

Okay, so I guess the lack of replies to your query is because it's quite odd!  Generally, your router not being able to get internet access shouldn't stop clients from reviving local DHCP info - including DNS addresses (even if they're not available due to the internet being down).

Can we assume that your setup is pretty standard :

ONT/PON > Router > LAN & WIFI clients

If there is any other network infrastructure or connections (including to telephone sockets) in there could you let us know what, and how it is connected!

 

*Query:  Does the current Vodafone router work as a caching DNS server, pushing its own address (192.168.1.1 or similar) out to clients, or does it direct clients to DNS servers directly?

View more options
network123
5: Helper

In addition to above, what software version is your router?

View more options
Jayach
16: Advanced member

@CrimsonLiar wrote:

*Query:  Does the current Vodafone router work as a caching DNS server, pushing its own address (192.168.1.1 or similar) out to clients, or does it direct clients to DNS servers directly?


Caching:

DHCP.png

 

View more options
andyhoe
2: Seeker

Thanks for the reply.

It is fairly standard and as you described. The only other things on the network are one dumb switch, one managed switch and three wired APs.

The only changes I've made to the router config are WiFi details and a few IP reservations.

Service is currently working although I cannot get to the router config page via a browser (doesn't even time out, just keeps on with the spinning wheel) and the Vodafone app says "App to router connection failed"

Wireshark shows my computer hitting the router IP and getting ACKs but I don't know enough what it should look like to know the difference.

Regarding your DNS query, it uses itself - 192.168.0.1

View more options
andyhoe
2: Seeker

At the moment I have no access to the router page so cannot tell unfortunately!

I'm loathed to reboot it as yesterday I spent probably 4-5 hours rebooting to get it to how it is now - a semi-working service, also while on the phone or in a chat to Vodafone support. Once the service is sort of working though, they lose interest and close the ticket.

View more options
Jayach
16: Advanced member

It worries me that you can't log into the router. I'm wondering if one the switches is causing some form of network storm and the router is just too busy to service the login.

I know you won't want to touch it just now, but next time you have to reboot disconnect everything from the router except for one device and see if you can connect and use the web interface O.K.

If would also probably be a good idea to back up your configuration and do a factory reset to clear everything down.

If with just one device you are unable to use the web interface O.K., it sounds like a faulty router.

View more options
andyhoe
2: Seeker

Agreed but there certainly don't seem to be excessive broadcasts when packet sniffing. Every time I reboot, I do take everything out but seems to make no difference.

 

Also the 4G backup will never kick in. When I tell support they ask me to reboot my router to test but I don't want to do that! The dongle works fine in a laptop, I believe there is a router issue but can't seem to convince anyone in support.

 

My job is as a network manager and if this happened to one of my devices there I would have easily got a replacement by now!

 

Next time I can get to the web interface I'll definitely try to factory reset 👍

View more options
network123
5: Helper

@Jayach wrote:

It worries me that you can't log into the router. I'm wondering if one the switches is causing some form of network storm and the router is just too busy to service the login.

I know you won't want to touch it just now, but next time you have to reboot disconnect everything from the router except for one device and see if you can connect and use the web interface O.K.

 


This is what I'd suggest as well. Does sound like a config gone wrong.

 

Sounds stupid, but are you running a second DHCP server causing havoc?

View more options
network123
5: Helper

@andyhoe wrote:

Also the 4G backup will never kick in. When I tell support they ask me to reboot my router to test but I don't want to do that! The dongle works fine in a laptop, I believe there is a router issue but can't seem to convince anyone in support.



Oh wow, I didn't even know this would work lol. I would say does it say your connected to mobile signal on the router settings, but... awkward.


@andyhoe wrote:

Next time I can get to the web interface I'll definitely try to factory reset 👍


I think there's a button at the back you can press IIRC.

View more options
Jayach
16: Advanced member

@network123 wrote:

I think there's a button at the back you can press IIRC.


Yes, hold it in for at least 10 seconds.

View more options
CrimsonLiar
14: Advanced member

Lol - I was trying to be diplomatic earlier "just in case".

I learnt the hard way don't leave ethernet cables just plugged into the switch at one end and just laying around at the other, someone will come around and plug the other end in too - just to tidy things up - hey presto network storm.

I'd probably be turning off the APs and switches initially to see if that cures the issue, before gradually reintroducing them one by one.  Check cables, dedicated uplink ports, subnets, etc as you go - but you'll know all of this already!

View more options
andyhoe
2: Seeker

Right, so the toaster tripped the power this morning and I'm back with no internet! Rebooted everything around 15 times so far, nothing is connected to the router apart from a laptop. Managed to get a DHCP address once but couldn't ping the router. Added a static IP and can ping the router but cannot web browse to it.

I have tried factory resetting 8 times, 6 of those nothing happened when I pressed the button. The other 2 times, the lights all came on and went out one by one. This doesn't seem to have actually reset anything though as my own SSID is still being broadcast.

Throughout all this the internet light has sat there flashing red 😠 guess I'm back on the phone but it's not really getting me anywhere.

View more options
CrimsonLiar
14: Advanced member

Considering your background would it be possible for you to borrow a router from somewhere (never met a network engineer who didn't have an old router or three hanging about somewhere), get your sign-in credentials and give that a go?

View more options
Jayach
16: Advanced member

When it all went down, instead trying to get it all back up, start slowly, just a wired device connected to the router after a factory reset. (the lights going out one by one usually signifies it has happened, but the SSID should have reset to default) If you are unable to log in to the router, and browse the settings like that it must be faulty.

View more options
andyhoe
2: Seeker

Well. unbelievably it's all working as it should!

Vodafone support said they'd send a new router, so in the meantime I looked around for spares, only had an expired Meraki unfortunately, also tried a PPPoE connection from my laptop but couldn't get that working. 

I tried one more factory reset and it did something different this time (power light flashing) and actually did factory reset itself. Believe me I must have tried this at least 50 times previously.

So it now connects as it should, 4G backup lights up when WAN disconnects (still can't get online with it but that's another issue to look at) and the phone light is on. I can also get to the web management and everything!

Thanks for everyone's input into this, no idea what caused it but happy to have it working again.

View more options
Jayach
16: Advanced member

I wonder if it got a firmware update this time? Don't suppose you made a note of it before?

View more options