Only one ethernet port works on BT mini connector

[Arthur_Brayne]

I have two BT mini connectors set up in the usual way, both on the same mains ring. In another room I have identical computers sat next to each other - both are connected to the 'receiving' connector. However, irrespective of which computer is plugged into which port and which cable is used, I only get internet on one PC. I've tried 6 different ethernet cables and 3 different connectors and only ever get a connection to one PC.

The only thing I haven't tested is the connecter attached to the router for a couple of reasons - it's not easily accessible, but more importantly, if it works on one ethernet port on the receiving end I can think of no logical reason why it shouldn't work on both.

Any ideas anyone, please?

[TimCurtis]

@Arthur_Brayne 

How are the PC's IP Addresses allocated? Is it by the router using DHCP or are the PC's ethernet ports assigned an IP Address?

[Arthur_Brayne]

Hi@TimCurtis 

Allocated by the router

[TimCurtis]

@Arthur_Brayne 

Well indeed yes.

I've just connected 2 of my PCs via the BT Mini connectors to my router and exactly the same happens to me. Mine were both using the routers DHCP as yours are.

Very strange and I have no explanation for that unfortunately.

I then changed 1 PC to manually fix it's IP Address rather than use the routers DHCP and it works. 

I wonder if you connect both ports of the mini connector at the router end to the router if that makes a difference. Thought of this after I'd put everything back to normal.

[Arthur_Brayne]

Thanks @TimCurtis 

I'll give it a try when I've got time

[pddco]

No, you should only have one connection to the hub at the master end. The slave  connectors should act like Ethernet switches with their two ports linked to the master port connected to the hub. No idea why they’re behaving differently. I’m wondering if a reset of the hub might help? 

[Arthur_Brayne]

@pddco 

I think you've misunderstood me.

There's a single connector (what you're calling the 'master') attached to the router and, at the other end, two PC's connected to the 'slave'. It's at this end where the issue is, i.e., I only get an internet connection on one output irrespective of which one I use.

[licquorice]

Weird, it's as though the 2 ports are just teed together rather than 2 discrete ports of an Ethernet switch. If so, the second port seems a pointless addition.

[pddco]

@Arthur_Brayne  I understood, but thought you were going to try putting two cables into the hub. One to each of the ‘Master’s” ports . Which is not how it should be done.  As @licquorice says, it’s weird. I’m sure I’ve seen user guides showing two PCs connected at the Slave. I mean why else would there be two ports? 

[pddco]

Did you try resetting the hub? I’m a bit rusty on IP stuff but Ethernet switches, being layer 2 devices, don’t really care about IP addresses. They’re more interested in MAC addresses ( I believe) to switch stuff to a physical device.  IP addresses are the domain of the router, that allocates them. The fact that once you manually assign an IP address to the second PC. And they both work fine, seems to say the switches are working and switching Ethernet frames correctly.  But the router is not correctly recognising where the request for an IP address is coming from and therefore not allocating one.. Which is why I thought a hub reset might help?