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#1 2020-05-13 08:42:39

shawniere
Member
Registered: 2020-04-26
Posts: 9

wired internet connection issue

I have recently added an old router into my network as an access point to extend my wifi.  It is working well except that my main machine is connected by ethernet and has been exhibiting weird behaviour since.  Whenever I boot up the wired machine while the access point is active I am not able to access the internet.  Following is output when I try

[~]$ ping -c 3 google.com
PING google.com (172.217.167.78) 56(84) bytes of data.
From _gateway (192.168.1.1) icmp_seq=1 Destination Net Unreachable
From _gateway (192.168.1.1) icmp_seq=2 Destination Net Unreachable
From _gateway (192.168.1.1) icmp_seq=3 Destination Net Unreachable

--- google.com ping statistics ---
3 packets transmitted, 0 received, +3 errors, 100% packet loss, time 2034ms

[~]$ ip link
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAUL\
T group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    2: enp3s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state \
UP mode DEFAULT group default qlen 1000
        link/ether d0:27:88:59:79:98 brd ff:ff:ff:ff:ff:ff

It looks like it is trying to access through the access point.  192.168.1.1 is the IP to the admin of the old router.  I have it set up with a static IP of 10.1.1.254.  My new router is 10.1.1.1
If I boot up with the access point disconnected all is fine.
This is a smallish problem but really annoying.  Is there a way make the wired machine, running Arch of course, go through the main router?
I know this sounds like a hardware problem but I feel like there must be a software solution.  It doesn't occur with other distros.
Thank you.

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#2 2020-05-13 12:29:14

seth
Member
Registered: 2012-09-03
Posts: 15,659

Re: wired internet connection issue

Compare w/ and w/o AP available the outputs of

ip a
ip r
sudo nmap --script broadcast-dhcp-discover

Also, how exactly do you configure your network? (dhcpcd, networkmanager, netctl, …)
Do you use systemd-resolved? The DNS resolution seems to work fine, if your NIC uses the wrong route, how does it get the google IP?

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#3 2020-05-14 01:45:53

shawniere
Member
Registered: 2020-04-26
Posts: 9

Re: wired internet connection issue

I have fixed my problem.  It was in fact a hardware issue.  Thank you for your suggestions.  It was comparing the outputs of ip a and nmap that indicated my computer was being assigned an IP by the AP which was obviously not set up properly as DHCP was still enabled.  Once this was disabled the problem went away.  I am still puzzled why this only affected my Arch installation and not my Mint installation.  Thank you for your patience.  I am very aware of the gulf between where my knowledge is and where it should be.

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#4 2020-05-14 04:59:48

seth
Member
Registered: 2012-09-03
Posts: 15,659

Re: wired internet connection issue

If

as DHCP was still enabled

means there was a rogue dhcp server the result is random and could in this case depend on when the (first) dhcp request is sent (before the wifi NIC is configured) and how the appearance of the wifi NIC is handled (voluntary switch)

Please always remember to mark resolved threads by editing your initial posts subject - so others will know that there's no task left, but maybe a solution to find.
Thanks.

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