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Ethernet connected but no internet

M

martin2a

macrumors newbie
Original poster
Feb 12, 2016
13
0
I have two Macs connected to the same router via ethernet cables.

One connects to the internet fine (via Safari), the other won't connect.

These are my settings per System Preferences -> Network:

Working Mac:

Ethernet Connected and green circle.
Location: Automatic
Status: Connected
Ethernet is currently active and has the IP address 192.168.61.2
Configure IPv4: Using DHCP
IP address 192.168.61.2
Subnet Mask: 255.255.255.0
Router: 192.168.61.1
DNS Server: 192.168.1.254

Failing Mac:

Ethernet Connected and green circle.
Location: Automatic
Status: Connected
Ethernet is currently active and has the IP address 192.168.1.146
Configure IPv4: Using DHCP
IP address 192.168.1.146
Subnet Mask: 255.255.255.0
Router: 192.168.1.254
DNS Server: 192.168.1.254

I wondered which addresses should be the same on both machines?
I noticed that the router address is different, should this be the same on both machines?

Any other suggestions to determine the problem would be much appreciated.
 
martin2a said:
I noticed that the router address is different, should this be the same on both machines?
Click to expand...

I would check your cables. The two machines appear to be using DHCP, so are getting their configurations automatically, but they appear to be on two different networks - as if they are plugged into two different routers.

A.
 
  • Like
Reactions: S.B.G and aristobrat
martin2a said:
No idea, I have limited knowedge?

Which of the addresses should be the same on both machines, I will try and manually amend them, if its possible?
Click to expand...
If both of your Macs are truly set for DHCP, then it seems unusual that the router would be giving them the IP addresses as you've listed. Not impossible, just a weird setup if that's truly what's happening.

If you switch the cables between the Macs, does the working Mac stop working, and the not-working Mac start working?

Typically, the subnet mask and router/DNS IP addresses are the same for computers on the same network segment.
 
martin2a said:
No idea, I have limited knowedge?

Which of the addresses should be the same on both machines, I will try and manually amend them, if its possible?
Click to expand...

Do you understand the for those two machine to "talk" to each other the must be in THE SAME first three sets of numbers (subnet) in each Computer station! Your switch has been VLANed into two subnetworks. That second IP( subnet it us in) has no connection to the Internet modem!
 
satcomer said:
Why are they on two different VLANs?
Click to expand...

Okay, there is a VOIP box plugged into the router, one of the machines was connected via a spare port on the VOIP.

They are now both plugged directly into the router. All the addresses are now the same on both machines except for IP Address.

But still I have no internet on one of the machines, what else should I check please?
 
I'd reboot the not working one. If it still doesn't work, to figure out if it's a computer issue vs. networking issue, I'd switch the Macs (or switch the cables) and see if the problem follows the computer or follows the cable.
 
Is the IP address on the 'not working' Mac now 192.168.61.x? If not, it is getting its IP address from a different router than the working Mac.
[doublepost=1455296727][/doublepost]By the way, are you sure this is right:

Working Mac:

Ethernet Connected and green circle.
Location: Automatic
Status: Connected
Ethernet is currently active and has the IP address 192.168.61.2
Configure IPv4: Using DHCP
IP address 192.168.61.2
Subnet Mask: 255.255.255.0
Router: 192.168.61.1
DNS Server: 192.168.1.254

The DNS server should be 192.168.61.1
 
aristobrat said:
I'd reboot the not working one. If it still doesn't work, to figure out if it's a computer issue vs. networking issue, I'd switch the Macs (or switch the cables) and see if the problem follows the computer or follows the cable.
Click to expand...

I switched the cables, but the outcome is the same?
[doublepost=1455297566][/doublepost]
JohnDS said:
Is the IP address on the 'not working' Mac now 192.168.61.x? If not, it is getting its IP address from a different router than the working Mac.
[doublepost=1455296727][/doublepost]By the way, are you sure this is right:

Working Mac:

Ethernet Connected and green circle.
Location: Automatic
Status: Connected
Ethernet is currently active and has the IP address 192.168.61.2
Configure IPv4: Using DHCP
IP address 192.168.61.2
Subnet Mask: 255.255.255.0
Router: 192.168.61.1
DNS Server: 192.168.1.254

The DNS server should be 192.168.61.1
Click to expand...


Both are now:
Subnet Mask: 255.255.255.0
Router: 192.168.1.254
DNS Server: 192.168.1.254

Working MAC IP Address: 192.168.1.140
Not working Mac IP Address: 192.168.1.146
 
JohnDS said:
That looks good. Can you try rebooting the not working Mac?
Click to expand...

Rebooted, unfortunately still no internet.

It seems that the ethernet settings now make sense and the network tab shows my ethernet as connected.

Perhaps I will have to look elsewhere for the reasons behind the lack of internet with the browser?
 
1. Which MAC was plugged into the VOIP box? The IP of the working one changed according to the last post.
2. Can the non-working MAC ping google.com (open terminal window and type "ping google.com") Reply with the output.
3. Do you have access to the router's LAN settings to see what IP addressing is configured?
4. What is / where is the Internet connection?
 
Open terminal and type:

ping google.com

What happens?

Then try

ping 216.58.216.23

What happens?
 
Mr. Buzzcut said:
1. Which MAC was plugged into the VOIP box? The IP of the working one changed according to the last post.
2. Can the non-working MAC ping google.com (open terminal window and type "ping google.com") Reply with the output.
3. Do you have access to the router's LAN settings to see what IP addressing is configured?
4. What is / where is the Internet connection?
Click to expand...

1) The working MAC.
2) ping: cannot resolve google.com unknown host
3) I'm not sure how to go about that, I'll do some research.
4) BT Broadband at home. One thing I noticed is that normally when you attach a new machine a BT set up menu appears with Parental Controls etc. , didn't happen this time.
[doublepost=1455303159][/doublepost]
JohnDS said:
Open terminal and type:

Open terminal and type:

ping google.com

What happens?

Then try

ping 216.58.216.23

What happens?
Click to expand...


ping: cannot resolve google.com unknown host

PING 216.58.216.23 (216.58.216.23): 56 data bytes
Request timeout for icmp_seq 0
Request timeout for icmp_seq 1
etc. still counting upwards
 
Interesting. It's going to become important to understand what plugs into what. Internet, router, VOIP, MACs, anything you have between the MAC and the Internet.

Can you ping 192.168.1.254?

Type "netstat -rn" in the terminal and reply with that too.
 
Mr. Buzzcut said:
Interesting. It's going to become important to understand what plugs into what. Internet, router, VOIP, MACs, anything you have between the MAC and the Internet.

Can you ping 192.168.1.254?

Type "netstat -rn" in the terminal and reply with that too.
Click to expand...

outcome of 192.168.1.254 same as 216.58.216.23

netstat -ms:
515/620 mbufs in use:
515 mbufs allocated to data
105 mbufs allocated to caches
512/654 mbuf 2KB clusters in use
0/170 mbuf 4KB clusters in use
0/0 mbuf 16KB clusters in use
2188 KB allocated to network (52.7% in use)
0 KB returned to the system
0 requests for memory denied
0 requests for memory delayed
0 calls to drain routines
 
If that is really your router and you can't ping it then we found much of your problem.

The command I listed has r and n, not m and s.

netstat -rn

Add ifconfig while you're in there!
 
On the non-working Mac in the network prefs under TCP, click on Renew DCHP lease and see if you get an different IP address.

Also, under the Proxies tab, make sure NOTHING is checked.
[doublepost=1455306039][/doublepost]Also, as an experiment, disconnect the VOIP box, reboot the router and reboot both Macs and see what happens.
 
Mr. Buzzcut said:
If that is really your router and you can't ping it then we found much of your problem.

The command I listed has r and n, not m and s.

netstat -rn

Add ifconfig while you're in there!
Click to expand...

Apologies, I can't respond further immediately but will be back ASAP.

I ran netstat -m, the s was a typo, I will come back with r and n.

Thanks for your support.
 
Also, you could try unplugging the ethernet cable from the Mac that is working and plugging it into the Mac that is not working in case the problem is a bad cable or router port.
 
On the Mac that is not working try the following:

System Preferences > Network > Click the lock to authenticate > Location: > Edit Locations... > Click [+] > Name it "New Location" > Click "Done" > Click "Apply
 
I wonder if that "VOIP box" (whatever that's supposed to be) is throwing a wrench into the works?

A couple of scenarios I would try:

1. Disconnect the VOIP box temporarily.
2. Plug both Macs into the router.
3. Power EVERYTHING off for 30 seconds, then reboot
How are the Macs now?

If both are ok, I might consider doing this:

Since the "working Mac" was connected to the VOIP box, I would do this:
1. Put an ethernet switch "after" the VOIP box
2. Connect both Macs to the switch
3. Power EVERYTHING off for 30 seconds, then reboot.
How are the Macs now?
 
I think you may be right, Fishrrman. I suggested unplugging the VOIP box a couple of posts ago.

I have a voip box myself and my recollection is that there are two ways to install it, either before or after the router. My recollection is also that the default setting are for the installation before the router and with those settings the VOIP box acts as a router and provides DHCP. It sounds as if those are the setting the OP is using, even though is VOIP box is connected after the router.

To connect the VOIP box after the router, you have to get into the settings and turn off its DHCP server or you will have two DHCP servers on the same network, which is a recipe for chaos.

Martin, can you tell us what VOIP service you are using and which VOIP box?
 
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