Devices with random MAC don't have internet - No white- / blacklist

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Devices with random MAC don't have internet - No white- / blacklist

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Devices with random MAC don't have internet - No white- / blacklist
Devices with random MAC don't have internet - No white- / blacklist
2022-09-24 19:19:34 - last edited 2022-10-02 13:46:18
Tags: #internet
Model: Archer C80  
Hardware Version: V1
Firmware Version: 1.11.0 Build 220425 Rel.43193n(4555)

Hello,

I have the problem that suddenly some devices aren't having an internet connection.

They can connect to the router (so it can't be blacklist) but just cannot connect to the internet and their phones say so.

The problem started yesterday morning while I haven't even made any changes to settings for a longer time (a few days).

Normally I know this behaviour when the whitelist is enabled, but neither the whitelist nor blacklist are turned on.

Additionally, an older device where it's unknown whether it even has the random MAC feature, also has no internet.

 

I already restarted the router few times. I won't reset it since I'd have to change all settings again and don't want to.

 

What could the problem be?

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#1
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1 Accepted Solution
Re: Devices with random MAC don't have internet - No white- / blacklist-Solution
2022-10-02 13:46:14 - last edited 2022-10-02 13:55:07

Found the problem and solution!

 

 

For context:

I connected the tplink router to my FritzBox router in order to extend the network and use the "Router Mode". When devices connect to a router, they get assigned an internal ip. It starts, for example, from 192.168.178.100 and new devices get an IP with the last three digits increasing, e.g. 192.168.178.100, 192.168.178.101, 192.168.178.102,... Some routers may work differently, have different settings or adjust IPs randomly and some devices may want their own IP. But speaking for the tplink router, it uses the mentioned way and adjusts the IPs with the last three digits increasing.

 

However, in my case, some IPs were also in use by devices connected to the FritzBox. E.g. a device "A" was connected to the FritzBox and had the IP 192.168.178.101. Now I tried to connect with my device "B" to the tplink router in which one other device "C" (IP 192.168.178.100) was also connected, so device "B" gets assigned the IP 192.168.178.101 as per mechanism of how the tplink router assigns IP addresses internally. However, as "B" had the same IP than "A", "B" no longer had internet access since that IP was reserved already within the FritzBox router for "A". But since the tplink router only connects to the FritzBox router as an external LAN device, it doesn't know what IPs are already in use or atleast does not do proper checks (tplink could maybe do pings, or something like that (I don't know exactly), to see whether an IP is reserved or not).

 

Solution:

First check which IPs, more specifically, the IP ranges, are used in the FritzBox router or any other router you connected your tplink router to.

For example, to my FritzBox router there were devices connected to with the IP 192.168.178.39 but also the ip 192.168.178.108.

I therefore decided to not use IPs within the range below 200 (the last three digits, e.g. the 100 in 192.168.178.100).

That means that my tplink router would not give any devices an ip address with the last three digits being below 200.

To change the range in the tplink router, follow the following steps:

1. Log in to the admin panel (e.g.  http://192.168.0.1/ or http://tplinkwifi.net).

2. Go to "Advanced".

3. Go to "Network" and then "DHCP Server".

4. Now change the values after "IP Address Pool:"

I have changed

- the first value from "192.168.0.100" to "192.168.0.200"

- kept the second value, which was set to "192.168.0.249"

Now, new devices that connect to the tplink router get an ip between 192.168.0.200 and 192.168.0.249.

 

Hope that it might help someone some day.

 

Best regards

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Re:Devices with random MAC don't have internet - No white- / blacklist
2022-09-24 21:53:18

  @dkb 

 

Hi,

 

If you take one of the devices you know have MAC randomization enabled and switch MAC randomization off, can this device than connect to the Internet via your C80?

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Re:Devices with random MAC don't have internet - No white- / blacklist
2022-09-24 22:25:58

  @woozle yes. Sorry forgot to add that. Only with one phone it doesn't work since it seems like it most likely has it enabled on default or we just don't know how to disable it.

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Re:Devices with random MAC don't have internet - No white- / blacklist
2022-09-25 15:20:57

  @dkb 

 

Maybe try to switch off (temporarily) the SPI Firewall and QoS and check if that makes any difference. 

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Re:Devices with random MAC don't have internet - No white- / blacklist
2022-09-28 16:43:32 - last edited 2022-10-02 15:00:34

  @woozle thank you for the response and sorry for my late reply. It looks like disabling SPI did potentially fix the issue. But what could be the reason for it?

 

// EDIT: 

It actually didn't help. The device randomly had internet, but now doesn't anymore. I don't know what it is that some devices randomly have internet and others don't. I write from my PC which has internet but my phone and that of someone else don't have.

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Re: Devices with random MAC don't have internet - No white- / blacklist-Solution
2022-10-02 13:46:14 - last edited 2022-10-02 13:55:07

Found the problem and solution!

 

 

For context:

I connected the tplink router to my FritzBox router in order to extend the network and use the "Router Mode". When devices connect to a router, they get assigned an internal ip. It starts, for example, from 192.168.178.100 and new devices get an IP with the last three digits increasing, e.g. 192.168.178.100, 192.168.178.101, 192.168.178.102,... Some routers may work differently, have different settings or adjust IPs randomly and some devices may want their own IP. But speaking for the tplink router, it uses the mentioned way and adjusts the IPs with the last three digits increasing.

 

However, in my case, some IPs were also in use by devices connected to the FritzBox. E.g. a device "A" was connected to the FritzBox and had the IP 192.168.178.101. Now I tried to connect with my device "B" to the tplink router in which one other device "C" (IP 192.168.178.100) was also connected, so device "B" gets assigned the IP 192.168.178.101 as per mechanism of how the tplink router assigns IP addresses internally. However, as "B" had the same IP than "A", "B" no longer had internet access since that IP was reserved already within the FritzBox router for "A". But since the tplink router only connects to the FritzBox router as an external LAN device, it doesn't know what IPs are already in use or atleast does not do proper checks (tplink could maybe do pings, or something like that (I don't know exactly), to see whether an IP is reserved or not).

 

Solution:

First check which IPs, more specifically, the IP ranges, are used in the FritzBox router or any other router you connected your tplink router to.

For example, to my FritzBox router there were devices connected to with the IP 192.168.178.39 but also the ip 192.168.178.108.

I therefore decided to not use IPs within the range below 200 (the last three digits, e.g. the 100 in 192.168.178.100).

That means that my tplink router would not give any devices an ip address with the last three digits being below 200.

To change the range in the tplink router, follow the following steps:

1. Log in to the admin panel (e.g.  http://192.168.0.1/ or http://tplinkwifi.net).

2. Go to "Advanced".

3. Go to "Network" and then "DHCP Server".

4. Now change the values after "IP Address Pool:"

I have changed

- the first value from "192.168.0.100" to "192.168.0.200"

- kept the second value, which was set to "192.168.0.249"

Now, new devices that connect to the tplink router get an ip between 192.168.0.200 and 192.168.0.249.

 

Hope that it might help someone some day.

 

Best regards

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#8
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