EC2: eth0: Could not set DHCPv4 address: Connection timed out

Question

Hi all,

our EC2 instance today crashed with the following logs in the syslog:
```
Nov 01 20:56:55 ip-10-1-0-236 systemd-networkd[1695219]: eth0: Could not set DHCPv4 address: Connection timed out
Nov 01 20:56:56 ip-10-1-0-236 systemd-networkd[1695219]: eth0: Failed
-- Reboot --
Nov 01 21:15:55 ip-10-1-0-236 kernel: Linux version 5.15.0-1049-aws (buildd@lcy02-amd64-042) (gcc (Ubuntu 9.4.0-1ubuntu1~20.04.2) 9.4.0, GNU ld (GNU Binutils for Ubuntu) 2.34) #54~20.04.1-Ubuntu SMP Fri Oct 6 22:04:33 UTC >
Nov 01 21:15:55 ip-10-1-0-236 kernel: Command line: BOOT_IMAGE=/boot/vmlinuz-5.15.0-1049-aws root=PARTUUID=24ca9e81-01 ro console=tty1 console=ttyS0 nvme_core.io_timeout=4294967295 panic=-1
```

there is a [similar question](https://repost.aws/questions/QUi1GW7UkqQDWrP8Sx90kiEA/ubuntu-instance-lost-connection-and-crash) on re:Post, but the answer sends the OP to an archived page, so the information is no longer visible. Any idea why the EC2 stalled?

Answer

Hello.

What kind of applications are you running on EC2?  
Also, is it possible that the application has increased the load on EC2?  
Please check the CPU usage rate and memory usage rate.

Answer

if you have nmap installed you can try 
```
sudo nmap --script broadcast-dhcp-discover -e eth0
```
to see what is going on.

Also maybe check the status of dhcp service and restart it.

EC2: eth0: Could not set DHCPv4 address: Connection timed out

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