0

I have a pretty complicated system going on and I need some help figuring out what I am doing wrong. I am not a computer engineer or have had much experience with RPI.

I am running two RPI's with a custom archlinux OS.

The more powerful RPI 4 b is running headless and acting as a node that is connected to the internet and a router (not internet connected).

The second RPI3b is the device that will communicate and provide data to the node that the node uploads to an internet server.

However, the node (RPI 4b) does not seem to detect the device (RPI3b).

I have configured the router with an SSID and passkey that should be accessible by the wifi of both RPIs.

When I log into the internet server site, I only see that the node is active but the device is not detected.

To figure out if there are issues with communication between the two, I have found the IP addresses of the node and the device.

When the node ping's the device I get a host, not detected command. The same thing happens when the device tries to ping the node.

When I try to find the hosts on the device by typing:

`getent hosts` I get:
127.0.0.1 localhost
192.168.0.100 node 

I check the RPI3b using ip address show

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc no queue state UNKNOWN group default glen 1000
    link <loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
        valid_lft forever preferred_lft forever
    inet6  ::1/128 scope host
        valid_lft forever preferred_lft forever
2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc fq_code1 state DOWN group default qlen 1000
    link/ether b8:27:eb:ef:b8:af brd ff:ff:ff:ff:ff:ff
3: wlan0:<BROADCAST, MULTICAST, UP,LOWER_UP> mtu 1500
mtu 1500 qdisc fq_code1 state UP group default qlen 1000
link/ether b8:27:eb:ba:ed:fa brd ff:ff:ff:ff:ff:ff
inet 192.168.0.2/24 brd 192.168.0.255 scope global dynamic noprefixroute wlan0
valid_lft 86153sec preffered_lft 75353sec
inet6 fe80:: ba27:ebff:feba:edfa/64 scope link
valid_lft forever preferred_lft forever

So I have now looked at the node and when I look at the ip address show this is what happens:

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc no queue state UNKNOWN group default glen 1000
link <loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_code1 state UP group default qlen 1000
link/ether b8:27:eb:ef:b8:af brd ff:ff:ff:ff:ff:ff
inet 192.168.0.10/24 brd 192.168.0.255 scope global dynamic eth0
** The raspberry pi4 is connected to the internet via an ethernet cable

3: wlan0:<BROADCAST,MULTICAST>mtu 1500 qdisc fq_code1 state DOWN group default qlen 1000

4:enp1s0u1u1: <BROADCAST,MULTICAST>mtu 1500 qdisc noop state DOWN group default qlen 1000
** not sure what this is, I have another ethernet cable connected to the configured router.

Then when I ask getent hosts it says:

127.0.0.1 node

It seems that the node just doesn't see the device. I am not sure what to do now and if this is an issue with the node OS.

I have tried restarting the RPI's and reflashed the OS for both the node and the device and inserted new SD cards. But it still shows the same thing. I also tried to physically connect the two RPIs via usb and HDMI cables and I got the same results on the internet server. That the device was not detected. I did not write the OS code, so I don't have much experience in that. Any suggestions would be very helpful.

  • Archlinux is normally an OS for expert users - by default everything needs to be configured. As you haven't told us what you did or what network manager you are using this is unanswerable. PS even making Archlinux work reliably on a Pi can be a challenge. – Milliways Mar 30 at 4:36
  • The OS was not created by me, I am using someone else's OS. I am not sure about the network manager. – Dena Mar 30 at 5:49
  • With no much experience about RPi I would suggest to use Raspbian instead of archlinux if possible. – Ingo Mar 30 at 12:14
0

The issue is now resolved. The issue was that I was connecting the node to two routers with the same IP address. Once I changed the IP address range of the router not connected to the internet, I could see that both RPIs were recognised by the router and the device could ping the node it was receiving the signal.

| improve this answer | |
  • Please accept your own answer with a click on the tick on its left side. Only this will finish the question and it will not pop up again year for year. – Ingo Apr 7 at 8:32

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.