[SOLVED] Router not handing out IPs

[jaymed]

Router not handing out IPs on some devices

Hello,

so my 4year old Netgear Nighthawk r7000 stopped giving out IPs last weekend but not to all devices!
my New iPhone will connect on 5ghz band but on 2.4ghz it will connect but have "No internet Connection" and 169.x.x.x address.
same issue with pretty much all Wifi devices but some connect on 2.4ghz and not on 5 and vice versa. there is no rime or reason. re-set Modem, router, all devices connected. Netgear firmware is V1.0.9.42_10.2.44 as this is the one with fastest speed. had it for long time without any issues. QOS is off, Access control is off. and i tried everything i can think off. reset network setting on iphone and ipads still no go

all devices connect instantly to my MiFi device so it has to be on rtrs side
Thanks in advance

 

[bill001g]

It is crazy if it works on some things and not others. In most router the router chip itself only has 1 data connection to the lan. This include the wifi chips and the switch chip that runs the lan ports. Now I suppose a router manufacture could run it different but in effect what it looks like is the router is hooked to a switch and the wifi radios are also hooked to the switch.

A phone has almost no diagnostic ability. Hopefully you have a PC that has this issue. Run wireshark and see what is different between the ones that work and the ones that don't DHCP is actually a extremely simple function when you just use the part that assigns IP addresses. The pc sends out a broadcast that says someone give me a IP, The router responds with a offer message and the pc responds that it will accept it.

My guess would be some bug that is blocking broadcast messages.

 

[kanewolf]

Your new iPhone could be causing problems with your router because of the random MAC address option. Try disabling that option on your WIFI.

It could also be a WIFI channel incompatibility. Maybe your router is set to channel 13 and your iPhone doesn't support it.

 

[jaymed]

It is crazy if it works on some things and not others. In most router the router chip itself only has 1 data connection to the lan. This include the wifi chips and the switch chip that runs the lan ports. Now I suppose a router manufacture could run it different but in effect what it looks like is the router is hooked to a switch and the wifi radios are also hooked to the switch.

A phone has almost no diagnostic ability. Hopefully you have a PC that has this issue. Run wireshark and see what is different between the ones that work and the ones that don't DHCP is actually a extremely simple function when you just use the part that assigns IP addresses. The pc sends out a broadcast that says someone give me a IP, The router responds with a offer message and the pc responds that it will accept it.

My guess would be some bug that is blocking broadcast messages.

Both my PCs are set to up with static IP and dont have this issue, this is only on WiFi, its on new iphone old ipad, old laptop (only happens on WIFi connection, LAN works ok). tried turning off the 20/40 coexistance,turned off smart connect, security is as always WPA2-PSK AES.
had this issue for about 4 days and when the lease is up the device that was connected to 5ghz will only connect to 2.4ghz where before i could switch between depending on haw far i was and what speed i needed.

 

[jaymed]

Your new iPhone could be causing problems with your router because of the random MAC address option. Try disabling that option on your WIFI.

It could also be a WIFI channel incompatibility. Maybe your router is set to channel 13 and your iPhone doesn't support it.

this is not just on new iphone, all wifi devices old and new have problems accessing IP, access control is off

 

[bill001g]

You really need to see what going on. Take the old laptop and load wireshark on it. You need to see what dhcp message it is sending out. You can force it to send messages by doing dhcp /release and dhcp /renew.

You should see the pc send out a broadcast dhcp discovery message. In theory the router will get this and reply.

You can also see the dhcp discovery messages from your phone on the pc running wireshark. Since it is sent out as a broadcast all devices will see it. You may or may not see the response from the router depending certain options in how the address was requested.

 

[gggplaya]

What's your client lease time set to? What's your DHCP range? I had this happen at a hotel I was staying at in the Bahamas. They were using a consumer grade router in the lobby to serve up Wifi. They had their DHCP range set to 50 users by default, and a 12 hour lease time. As you can guess, in a hotel with over 100 rooms, people were going crazy in the lobby because they couldn't connect to the wifi. Then come back later and it would work.

I worked with the manager and explained my theory. He allowed me to change the DHCP lease to 250 users and a lease time of 4 hours. He got no more complaints!

 

[jaymed]

What's your client lease time set to? What's your DHCP range? I had this happen at a hotel I was staying at in the Bahamas. They were using a consumer grade router in the lobby to serve up Wifi. They had their DHCP range set to 50 users by default, and a 12 hour lease time. As you can guess, in a hotel with over 100 rooms, people were going crazy in the lobby because they couldn't connect to the wifi. Then come back later and it would work.

I worked with the manager and explained my theory. He allowed me to change the DHCP lease to 250 users and a lease time of 4 hours. He got no more complaints!

DHCP is set 252 IPs so its not that as i have under 20, not sure where the lease is set

 

[jaymed]

You really need to see what going on. Take the old laptop and load wireshark on it. You need to see what dhcp message it is sending out. You can force it to send messages by doing dhcp /release and dhcp /renew.

You should see the pc send out a broadcast dhcp discovery message. In theory the router will get this and reply.

You can also see the dhcp discovery messages from your phone on the pc running wireshark. Since it is sent out as a broadcast all devices will see it. You may or may not see the response from the router depending certain options in how the address was requested.

downloaded wireshark but it looked like i needed another sw to make it work, this tool might be above my paygrade

 

[bill001g]

Just follow the install instructions. Wireshark very technically is only a data formatting software. The actual capture software is called PCAP. There was some recent change to the version it loads I think. In any case wireshark should offer to load this software when you install it. If you REALLY wanted to you can use the the winpcap or whatever they call it now and process the data yourself. Wireshark makes it so easy nobody would think to do it manually.