LAN oddity

[opps]

Is the primary router the one that doles out IP addresses?

Have you tried to PING the primary router?

Another thing to consider is the 2.4Ghz channels. Here in Europe we use channels 1-13, in the USA they use 1-11. From memory many Apple laptops will, by default, only work between 1 and 11.

It might be useful if you open a command prompt (via an ethernet cable) and TRACERT a known IP address, eg the primary MODEM or google ( 142.251.46.174 ).

 

[Harry Bloomfield]

Is the primary router the one that doles out IP addresses?

Yes, it's the one connected to the FTTC, and all the others, have their DHCP disabled.

Have you tried to PING the primary router?

Numerous times, when I am able to connect to the internet, ping works fine, when there is no internet, their is no ping responce.

Another thing to consider is the 2.4Ghz channels. Here in Europe we use channels 1-13, in the USA they use 1-11. From memory many Apple laptops will, by default, only work between 1 and 11.

Main is on 1; second is on 7; hut is on also on 1

Curiously - I have been trying to sort out a smart TV which had amongst other issues, off and on internet access. Then the access died completely, it could see the access points, but unable to connect to any of them. I pulled that apart this afternoon, to take a look. I would seem to have sorted it out, but it, like my laptop was only able to connect to the hut repeater.

Might some of the problems be due to too many items connecting via wifi?

Below is what my main router shows, but it has my Pavillion laptop wrong, it's not 241, it should now show 195. It doesn't differentiate between wired and wifi, for things connected via my second router, under Ethernet, but the pasted image below that does.

MAIN..

SECOND..

 

[Harry Bloomfield]

Weirdly, my main router is continuing to report the IP of my laptop as 241 (exactly as is the upper screen grab), rather than it's new actual IP of 195, and despite refreshing the main router's web page some hours later. I wonder if that might have some relevance?

 

[opps]

You seem to have 3 devices using 192.18.1.221

What happens if you tell your laptop to use 192.168.1.241

From memory, a domestic router can deal with 32 wifi clients at any given time.

 

[Harry Bloomfield]

You seem to have 3 devices using 192.18.1.221

Not that I could see, but it has somehow allocated 211 twice, to similar devices. 221 is my IP cam. Don't forget, they are the listings from two separate routers, so some device IP's will appear in both lists.

What happens if you tell your laptop to use 192.168.1.241

It was allocated 241, at the beginning of all this going wrong. It seems quite happy, on 195 since yesterday, though only able to get a full connection to my nearest/second router. My main router, is still mistakenly reporting my Pavilion laptop, as being on 241.

At the moment, I am thinking of reconfiguring the whole lot... Because more and more devices are failing to connect.


Move the main router, and everything else with an IP below 200, to below 100. ie changing 173 to 073. Reserving all of the IP's below 100.

I'm not even sure that main router will allow those IP's. It's the Plusnet standard supply of FTTC modem, and is quite peculiar.

 

[hllns]

Not that I could see, but it has somehow allocated 211 twice, to similar devices. 221 is my IP cam. Don't forget, they are the listings from two separate routers, so some device IP's will appear in both lists.

Double allocation shouldn't normally occur with DHCP allocation as the client (and sometimes the server) will check if the address is in use.

It was allocated 241, at the beginning of all this going wrong. It seems quite happy, on 195 since yesterday, though only able to get a full connection to my nearest/second router. My main router, is still mistakenly reporting my Pavilion laptop, as being on 241.

Whilst the information on the router may be useful I'd not rely on it, I'd look at the clients and check which DHCP server it thinks it's fetched an address from (ipconfig /all on windows will show this) as it still sounds like there are multiple DHCP servers to me, if the address ranges are the same but the gateway address differs it would produce symptoms similar to what you're seeing, you should also be able to see if the gateway differs from ipconfig /all.

Simplify the test scenario, test using a wired connection to each router whilst disconnecting the second router from the first, the laptop should be able to fetch an address whilst connected to the first router but if the only DHCP server present is on the first you shouldn't be able to fetch an address via DHCP at all on the second.

 

[opps]

Not that I could see, but it has somehow allocated 211 twice, to similar devices. 221 is my IP cam. Don't forget, they are the listings from two separate routers, so some device IP's will appear in both lists.



It was allocated 241, at the beginning of all this going wrong. It seems quite happy, on 195 since yesterday, though only able to get a full connection to my nearest/second router. My main router, is still mistakenly reporting my Pavilion laptop, as being on 241.

At the moment, I am thinking of reconfiguring the whole lot... Because more and more devices are failing to connect.


Move the main router, and everything else with an IP below 200, to below 100. ie changing 173 to 073. Reserving all of the IP's below 100.

I'm not even sure that main router will allow those IP's. It's the Plusnet standard supply of FTTC modem, and is quite peculiar.

Sorry, my bad. In image 1 there were indeed only two on 211.

I don't understand how two devices with different MAC addresses can be assigned the same IP address.

 

[hllns]

Sorry, my bad. In image 1 there were indeed only two on 211.

I don't understand how two devices with different MAC addresses can be assigned the same IP address.

DHCP leases are an allocation of an address for a certain amount of time, standards compliant DHCP servers won't allocate an address it's already assigned a lease for but if it's a device where it doesn't have persistent internal storage and it's powered off it's possible.

If you have multiple DHCP servers serving overlapping or the same address pool you could possibly get double allocation, there are normally mitigations in place for the server and client to check if an address is in use on the same physical network at the time it's allocated, if you have laptops or devices in some kind of sleep mode or they only connect intermittently this can stymy it.

 

[Harry Bloomfield]

Sorry, my bad. In image 1 there were indeed only two on 211.

I don't understand how two devices with different MAC addresses can be assigned the same IP address.

I think that was probably a peculiarity of the Plusnet main router telling lies.

Another update, and some progress....

I have reconfigured all the routers, changing the 173, and etc. IP numbers to 73 etc. simply dropping the 1, reserving 0 to 100 as not being in the DHCP IP pool.

That meant 101 to 255 were available for the DHCP pool of IP's.

On rebooting the routers, everything came back on and worked fine, except my laptop. My laptop was only able to gain internet access, but this time via the main router, my laptop was given an IP of 241 - I'll try it later, setting it on the main router, to use an IP in the sub 100 range, to see if that helps. All other phones, pads etc. were able to connect to any router.

Simplify the test scenario, test using a wired connection to each router whilst disconnecting the second router from the first, the laptop should be able to fetch an address whilst connected to the first router but if the only DHCP server present is on the first you shouldn't be able to fetch an address via DHCP at all on the second.

The Pavilion laptop, lacks a wired LAN socket, it's wireless only.

 

[Harry Bloomfield]

The Pavilion laptop, lacks a wired LAN socket, it's wireless only.

I've just done a bit more experimentation, with my laptop wifi and found...

Main router 2g OK, 5g OK

Secondary 2g NO, 5g OK

Hut 2g OK, 5g was too weak to test a connection. OK = connects, and with normal access.

Now, why would it be able to connect to the 5g port of the second router, but not the 2g port? There is nothing wrong with the routers 2g port, because various other items are now connecting to it. There nothing wrong with the laptops port, because it connects fine with the other two routers.

 

[Harry Bloomfield]

Another update...

I now have the laptop connecting to the 2g port of the second router. What I hadn't realised was, my laptops 2g port was configured to use an IP of 195, instead of DHCP. The 5g port was set for it's default of DHCP.

 

[old duffer]

Only the main router, issues the address requests. The second and third routers have DHCP turned off. The 54 free addresses seems to be more than adequate, plenty of unused IP's.

If my laptop can connect to the hut access point, and various things are successfully connected to the access points of both my main and second router, how come my laptop cannot and all of a sudden?

can I suggest that you spend a little time on youtube on basic networking

 

[Harry Bloomfield]

can I suggest that you spend a little time on youtube on basic networking

All working absolutely fine now, and I never identified the cause..

I never managed to identify anything amiss with my setup, or setting, and nor did anyone else. My best guess is that that my main router, the one in charge of control of the DHCP, the standard issue by Plusnet for FTTC, became very confused. I repeat - all I did to sort things out, was to revise the all IP allocations from beginning at 173, to 073.