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Network Issues

Solutions for network and connectivity problems.

Cannot Ping SBC​

Symptoms​

ping 10.0.0.1
# Request timeout

Solutions​

  1. Verify Cable Connection

    • Ethernet LED on port
    • Firm cable connection
    • Try different cable

  2. Check PC Network Config

    # Linux
    ip addr show eth0
    # Should show 10.0.0.x

    # Set IP if needed
    sudo ip addr add 10.0.0.2/24 dev eth0

  3. Disable Firewall

    # Linux (temporary)
    sudo ufw disable

    # Or allow specific traffic
    sudo ufw allow from 10.0.0.1

SSH Connection Refused​

Error​

ssh: connect to host 10.0.0.1 port 22: Connection refused

Solutions​

  1. Verify SSH Service

    # On SBC (via serial)
    systemctl status sshd

    # Start if needed
    systemctl start sshd

  2. Check Credentials

    • Username: root
    • Password: root

  3. Verify IP Address

    # On SBC
    ip addr show eth0

No Video Stream​

Symptoms​

  • GStreamer pipeline runs
  • No video appears
  • Black screen

Solutions​

  1. Check GStreamer Pipeline

    # Test with videotestsrc
    gst-launch-1.0 videotestsrc ! autovideosink

  2. Verify UDP Port

    # Linux - allow port 5000
    sudo ufw allow 5000/udp

  3. Check Network Bandwidth

    # Test with iperf3
    iperf3 -c 10.0.0.1

IP Address Conflicts​

Symptoms​

  • Intermittent connectivity
  • Wrong device responds
  • Connection drops

Solutions​

  1. Check IP Addresses

    # List all devices on subnet
    nmap -sn 10.0.0.0/24

  2. Use Static IP

    # On SBC
    cat > /etc/systemd/network/10-eth0.network << 'NETEOF'
    [Match]
    Name=eth0

    [Network]
    Address=10.0.0.1/24
    NETEOF

  3. Change Subnet

    • Use 192.168.x.x range
    • Update both SBC and PC

DNS Not Working​

Symptoms​

  • Can ping IP addresses
  • Cannot resolve hostnames
  • ping google.com fails

Solution​

DNS is not configured on SBC by default. Use IP addresses or configure DNS:

# Temporary
echo "nameserver 8.8.8.8" > /etc/resolv.conf

# Permanent
cat > /etc/systemd/resolved.conf << 'DNSEOF'
[Resolve]
DNS=8.8.8.8
FallbackDNS=1.1.1.1
DNSEOF

systemctl restart systemd-resolved

Quick Diagnostic Commands​

# Check interfaces
ip addr

# Check routes
ip route

# Test connectivity
ping 10.0.0.1

# Check ports
netstat -tlnp

# Check firewall
sudo ufw status