LAN oddity

Harry Bloomfield

Harry Bloomfield

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My laptop is presently connected to the Internet, via my phones wifi hotspot, because it is unable to get Internet access via either of my main router, or a second one local to my laptop. The second one is connected to the main one, via a LAN cable, with the main router providing DHCP.

I can connect via wifi to either router, on 2g or 5g, but all four show 'no internet'. If I connect, and try to load the router web page, it fails.

A Fire Cube, has for several days, on and off, been complaining it has no Internet. I tried rebooting it several times, it has a wired connection, replaced it's cable, and one thing that got it connected today, was rebooting the second router. Some while later, my laptop lost it's connection to the second router, and I have been able to regain it since.
 
foxhole said:
Have you rebooted router, checked isp has no local outage?
Click to expand...

Both routers rebooted several times, as have everything else too. It cannot be ISP, because TV has streamed just fine throughout.

It must be a local LAN issue, because TV is connected to router, laptop appears to connect, but showing no internet, yet I cannot get to the same routers ettings webpage.
 
Check the router IP addresses aren't the same, check that both router ip addresses are outside the address range of the DHCP server.
 
oldbutnotdead said:
Check the router IP addresses aren't the same, check that both router ip addresses are outside the address range of the DHCP server.
Click to expand...

Main router has a fixed IP of 173, second router 176, garden extender 178. Then I have a fourth print router, which is only powered when I need to print. Entire range from 100 to 200, is disabled from DHCP allocation. 201 to 255 is free for DHCP use.

It does smell like an IP clash causing the problems, but I stumped as to how.
 
You're not using the WAN port to link the sub router to the main router are you? (Could get all manner of bizarre NAT with that setup).
Have a look at subnet settings on the laptop.
TRY using .1 to .50 for the dhcp range.
And last (just checking) these are all 192.168.xxx.xxx addresses?
 
oldbutnotdead said:
You're not using the WAN port to link the sub router to the main router are you? (Could get all manner of bizarre NAT with that setup).
Click to expand...

No, LAN port, to LAN port and working fine for years..
oldbutnotdead said:
TRY using .1 to .50 for the dhcp range.
Click to expand...

I could do, below 173 is entirely unallocated.

oldbutnotdead said:
And last (just checking) these are all 192.168.xxx.xxx addresses?
Click to expand...

Yes, but I spotted an oddity yesterday, when my laptop was actually connected to the router, and had internet access via the router....

I happened to check the table of connected devices in the main routers web page. It showed everything with a 192.168.1.??? - Except my laptop, which was connecting somehow, with an IP of (I think) 169.???.???.??? - Whatever, definately not a 192 address, but connected, it was. I didn't think it was possible?
 
169 etc is a loopback address so lappie isn't actually connecting fully (can't remember how far up the stack that fail sits). Have a look at firewall settings (on laptop mainly)
 
oldbutnotdead said:
Oh yeah, try setting a static address on the laptop.
Click to expand...

It still complains no internet, on 2g, 4g, on both my main router, and my second router, though it will show connected. I then tried connecting it to my router out in the garden, in the hut. It connects to that, reasonably reliably, but not very fast, barely any signal. Hut router, is an extender, connecting via wifi, to my main router.

I set it up with a permanent IP, in my main routers settings, made no difference to the above, I then gave it the same fixed IP in the laptops settings, again no difference.

When connecting to my main, or secondary router, it takes several minutes, and even when connected, I cannot access those routers webpages, I can though, do both via the extender in the hut.
 
Harry Bloomfield said:
Main router has a fixed IP of 173, second router 176, garden extender 178. Then I have a fourth print router, which is only powered when I need to print. Entire range from 100 to 200, is disabled from DHCP allocation. 201 to 255 is free for DHCP use.

It does smell like an IP clash causing the problems, but I stumped as to how.
Click to expand...

You have created something that is unnecessarily complex for device connection as you have created a rule that the master router cannot know about i.e. only issue from start to end range..based upon the connected router....i'm surprised it ever works.

Assuming you have simple routers on the network, then there can only be one router issuing an address....now you can tell it where to start the pool from but when it gets a request from another router to say "give me an address between 100-200 but the router has been told "only issue from 201-255...what did you think would happen?

You fix this by removing the restricted range on the router that is the DHCP issuer, let it issue what it wants.
With the other routers, you can keep the restrictions of the range.
 
old duffer said:
Assuming you have simple routers on the network, then there can only be one router issuing an address....now you can tell it where to start the pool from but when it gets a request from another router to say "give me an address between 100-200 but the router has been told "only issue from 201-255...what did you think would happen?
Click to expand...

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?
 
Are the SSIDs all the same? (Assuming you're using Windows) have a look at each connection property page, make sure there's nothing weird going on (especially in the Advanced tabs- look for odd stuff like authenticator method or randomised MAC address -some APs really hate them).

Try using your phone to connect to WiFi (switch mobile data off, Android is very good at falling back).

Try disconnecting everything except the main router, see if you can connect to that on its own- make sure you shut down the wireless link from the shed.

If you can connect to the main router and access the config pages, check what devices are showing as connected. If there are any you don't recognise, change the WiFi passwords and admin passwords, consider MAC filtering on the routers

Try connecting to the sub router while it isn't connected to the main router (you'll need static ip on the laptop for that to work.

The long delay/partially failed connection could be signs of a busy network- either router on the way out or pirates.
 
[UPDATE] Addresses 0 to 200 are not in the DHCP pool, 200 to 255 are in the pool. My laptop was allocated an IP of 241 and so far as I could determine, nothing was clashing with that IP.

I have just reconfigured the laptop, to an IP of 195, which then allowed it to connect to my second router, with internet access, the one nearest to it, via the 2g port. Connection and internet access, is near instant.

Situation now is...

Main router, can show connected to either 2g, or 5g - but no internet, no access to anything on the LAN

Second router, connects to 2g, all works, 5g as main router.

Hut router, connects to 2g, all works, 5g as main router.
 
oldbutnotdead said:
169 etc is a loopback address so lappie isn't actually connecting fully (can't remember how far up the stack that fail sits). Have a look at firewall settings (on laptop mainly)
Click to expand...

AFAIK the 169.xxx.xxx.xxx is (AFAIK) exclusively a MS computer complaining that it has not been assigned a valid IP address

www.lifewire.com

How Automatic Private IP Addressing (APIPA) Works in Windows

Automatic Private IP Addressing (APIPA) allows DHCP clients to obtain addresses even when the local DHCP server cannot provide one.
www.lifewire.com www.lifewire.com

From memory, the loopback address is 127.0.0.1
 
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