Some DHCP questions are not answered in documentation.

[Holgi0811]

Hi guys,
I have some dhcp related questions:

• Is it possible to reset dhcp leases?
• What is dhcp range, full subnet?
• Is it possible to use fixed dhcp addresses?
• Is there a bug in Version V2.2.16? "save dhcp" command is not working. Device is receiving a new ip every day on wake up.

Thank you

[hmueller01]

Hi Holgi ;-)

What is dhcp range, full subnet? -> No:

    dhcp_lease.start_ip = config.network_addr;
    ip4_addr4(&dhcp_lease.start_ip) = 2;
    dhcp_lease.end_ip = config.network_addr;
    ip4_addr4(&dhcp_lease.end_ip) = 128;
    wifi_softap_set_dhcps_lease(&dhcp_lease);

Is it possible to use fixed dhcp addresses?
README.md says only by saving the DHCP table.

If you save your DHCP table (save dhcp) ESP comes up with lease time set to 100000 after reboot.
If a device connects, the lease time gets set to 120 = 2h. So after a day it unfortunately gets a new IP.

I plan to open a PR to make the lease time changeable ...

[hmueller01]

From ESP SDK documentation:
bool wifi_softap_set_dhcps_lease_time(uint32 minute)
Set ESP8266 SoftAP DHCP server lease time, 120 minutes by default.
uint32 minute: lease time, uint: minute, range: [1, 2880].

[hmueller01]

See #549