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DHCP not working for Ethernet / Plusnet Hub One

rossbrown
Newbie
Posts: 4
Registered: ‎04-02-2020

DHCP not working for Ethernet / Plusnet Hub One

Afternoon all. Well this one's got me stumped - so hoping the hive mind can sort me out!

Relatively new Plunet customer, no issues with service now it's up and running, except for the one machine connected via Ethernet. 

I work from home a couple of times a week, in a converted shed in the garden (known as the Shoffice). All kitted out, very nice it is too. 

My main machine in the Shoffice is a relatively new Mac mini, which I don't leave in the Shoffice when I'm not in there for obvious reasons. 

The machine is connected by a looooong Ethernet cable back to the router. All works fine, sometimes. 

Every time I connect the machine, it shows I have an IP address on the Mac (via the DHCP lease) but there's no Internet connection. This sometimes resolves itself after 10 minutes or so. 

As I write...

Mac says it has an IP address (192.168.1.90) but the machine doesn't show up in the DHCP table in the web admin panel or in the Devices list.

Or I'll get the opposite; the web admin panel says I have an IP address allocated (always 192.168.1.90), the machine appears in the Devices list but the Mac says I'm not connected (sometimes when the Mac is showing in Devices and I click on it, it says there's an IP address allocated but that the machine isn't connected). 

If I'm lucky the stars align, the IP address is allocated and the machine sees it - and I can do some work. 

I even bought a small hub, to leave permanently connected via Ethernet in the hope that would keep the link "alive" but that didn't work either. 

I'm sure there's something really obvious I'm missing, so any help or advice appreciated! 

Thanks in anticipation,

Ross

5 REPLIES 5
bill888
Aspiring Champion
Posts: 1,079
Thanks: 184
Fixes: 32
Registered: ‎18-10-2008

Re: DHCP not working for Ethernet / Plusnet Hub One

Assuming neither the Hub One or Mac are faulty, and Mac works fine when wired to Hub One with a short ethernet cable.

 

How long is the new ethernet cable?

Was it a fixed length patch cable with factory moulded RJ45 plugs on the ends, or did you lay cable and install wall mounted sockets at either end of the cable?

Did you use best quality 'pure copper' exterior grade cable to the shed?  (and not cheap 'Copper Clad Aluminium' CCA cable)

Does Mac report what the ethernet speed of its ethernet port?  ie. should be 1 Gbps

Try pinging the router (192.168.1.254) continuously and see if there is any packet loss/lag.

 

fwiw, if the cable can't handle 1 Gbps speed, you could perhaps install a 100 Mbps ethernet switch to force the speed to 100 Mbps and see if it helps.  eg. TPlink TL-SF1005D costs less than a tenner.

 

 

rossbrown
Newbie
Posts: 4
Registered: ‎04-02-2020

Re: DHCP not working for Ethernet / Plusnet Hub One

Thanks for the response, in answer to your questions:

> How long is the new ethernet cable?

50m cable. 

> Was it a fixed length patch cable with factory moulded RJ45 plugs on the ends, or did you lay cable and install wall mounted sockets at either end of the cable?

Laid cable, and got an electronics engineer friend of mine to fit RJ45s to the ends. 

> Did you use best quality 'pure copper' exterior grade cable to the shed?  (and not cheap 'Copper Clad Aluminium' CCA cable)

I admit it is CCA but it's Cat6 for outdoor use, so is good quality (or better than 'typical' CCA shall we say). 

> Does Mac report what the ethernet speed of its ethernet port?  ie. should be 1 Gbps

It doesn't report the speed of the port - but when it connects as it should, the speed shows as 1 Gbps.

> Try pinging the router (192.168.1.254) continuously and see if there is any packet loss/lag.

I can't ping it when it doesn't work (for example, I am told by the Mac that it has an IP address) but the router says it's not connected. So when I try a ping, I get the response "No route to host".

> fwiw, if the cable can't handle 1 Gbps speed, you could perhaps install a 100 Mbps ethernet switch to force the speed to 100 Mbps and see if it helps.  eg. TPlink TL-SF1005D costs less than a tenner.

The ethernet port on the Mac self-configures depending on what it's receiving and the Cat6 cable is rated for up to 10-Gigabit BASE-T and, as I said in my original post, it does more often than not work after being left for a few minutes to handshake (forcing the lease to renew usually does the job for example). 

I tried to force the speed to 100 Mbps by connecting a TP-Link Ethernet switch/hub but that didn't sort the problems annoyingly (about to go back to Amazon). 

If I reboot the router, the chances are it will all work. That's not so bad in the morning when the kids are at school etc but, right now, it would cause a bloodbath! 

(As I'm about to send this, I've pinged again, and got 0 per cent packet loss and a time averaging 3ms across 10 pings. Confusing isn't it!).

 

rossbrown
Newbie
Posts: 4
Registered: ‎04-02-2020

Re: DHCP not working for Ethernet / Plusnet Hub One

Update, did the Ping again (Ethernet now working again), a Speedtest (results below) and the ethernet interface shows link speed of 1Gbit/s

 

Ping has started…

 

PING 192.168.1.254 (192.168.1.254): 56 data bytes

64 bytes from 192.168.1.254: icmp_seq=0 ttl=64 time=1.151 ms

64 bytes from 192.168.1.254: icmp_seq=1 ttl=64 time=1.356 ms

64 bytes from 192.168.1.254: icmp_seq=2 ttl=64 time=1.262 ms

64 bytes from 192.168.1.254: icmp_seq=3 ttl=64 time=1.168 ms

64 bytes from 192.168.1.254: icmp_seq=4 ttl=64 time=1.156 ms

64 bytes from 192.168.1.254: icmp_seq=5 ttl=64 time=1.272 ms

64 bytes from 192.168.1.254: icmp_seq=6 ttl=64 time=1.188 ms

64 bytes from 192.168.1.254: icmp_seq=7 ttl=64 time=1.288 ms

64 bytes from 192.168.1.254: icmp_seq=8 ttl=64 time=1.156 ms

64 bytes from 192.168.1.254: icmp_seq=9 ttl=64 time=1.416 ms

 

--- 192.168.1.254 ping statistics ---

10 packets transmitted, 10 packets received, 0.0% packet loss

round-trip min/avg/max/stddev = 1.151/1.241/1.416/0.088 ms

 

Speedtest (using speedtest.net):

Ping 13ms, Download: 59 Mbps, Upload: 16 Mbps

 

 

bill888
Aspiring Champion
Posts: 1,079
Thanks: 184
Fixes: 32
Registered: ‎18-10-2008

Re: DHCP not working for Ethernet / Plusnet Hub One

If you still have an offcut of the original cable, strip and inspect the wires within cable to see if they are multi-strand or single core ?

The RJ45 plugs are different for each type of wires. ie. not interchangeable.

 

If the wires are single core, I personally would have installed wall mounted sockets for a few quid more.  (The individual wires are just punched into the rear of the RJ45 socket one at a time - plenty of Youtube HowTo videos)

Only other suggestion is to try any other old router instead of Plusnet hub on the long cable, to see if Mac can reliably get an IP from the router, and ping the router without problems to help you try and narrow down what may be causing the problems.

Another suggestion is put a computer on each end of the cable (one wired to hub), and use something like iperf3 to perform a multi-thread speed test of the cable and see if it will transfer data upto 1Gbps in both directions or collapse in a heap.

 

 

 

 

 

rossbrown
Newbie
Posts: 4
Registered: ‎04-02-2020

Re: DHCP not working for Ethernet / Plusnet Hub One

Hi Bill

> If you still have an offcut of the original cable, strip and inspect the wires within cable to see if they are multi-strand or single core ?

> The RJ45 plugs are different for each type of wires. ie. not interchangeable.

I need to correct something, my bad: one end of the cable is the existing RJ45 that came with the cable, the other isn't connected to an RJ45, we changed plans. It's wired into a wall mounted socket, cleaner job, easier than wiring an RJ45 (I haven't sunk the box into the wall yet, which is why I forgot!). The box, sits a few feet from the router/modem. 

As I said in my additional messages, all is now working fine - at full speed - for some reason. Nothing's been restarted or changed, it's just started working. 

Which is great - but annoying, as there's no reason for the change.