es, a DHCP lease expiring could explain why your Raspberry Pi stops working and you're unable to connect via SSH. When a DHCP lease expires, the Raspberry Pi will lose its IP address and will no longer be able to communicate with other devices on the network.

Here are some steps you can take to further diagnose the problem:

Check your router's DHCP lease time. The DHCP lease time is the amount of time that a device is allowed to use an IP address before it needs to renew the lease. If the lease time is too short, your Raspberry Pi may be losing its IP address too frequently.
Try renewing the DHCP lease manually. You can do this by running the following command:
"
sudo dhclient wlan0
"

If this is successful, your Raspberry Pi will be assigned a new IP address and you should be able to connect to it again.
3. Check your router's DHCP server logs. These logs may contain information about why the DHCP lease expired.
4. Try restarting your router and Raspberry Pi. This can sometimes fix minor network problems.
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