WiFi.setHostname() not working

[dsilletti]

Board

ESP32

Device Description

plain module

Hardware Configuration

N/A

Version

latest master

IDE Name

Arduino IDE

Operating System

macOS 12.1

Flash frequency

40Mhz

PSRAM enabled

no

Upload speed

115200

Description

WiFi.setHostname() does not work, hostname remain always esp32-XXXXXX

Sketch

WiFi.disconnect(true,true);
delay(1000);
WiFi.mode(WIFI_STA);
esp_wifi_set_country_code("IT", true);
WiFi.setHostname("hostname");

Debug Message

N/A

Other Steps to Reproduce

WiFi.setHostname("hostname");

I have checked existing issues, online documentation and the Troubleshooting Guide

• I confirm I have checked existing issues, online documentation and Troubleshooting guide.

[me-no-dev]

how did you test this? it's often that the DHCP server might cache the hostname

[dsilletti]

@me-no-dev I power cycled the Wi-Fi router that provides the DHCP server several times, power cycled the esp32 several times, but the hostname I see on the router is always esp32-XXXXXX

[JonGordon123]

On most routers if you want to clear the cache, you have to reset it using the reset button... and not just power cycle it. You could... connect to a different router, or reset the router, or change the esp32 MAC address to confirm the hostname shows up in the router.

[me-no-dev]

I have mikrotiks here for routers and they have "clear leases" option that allowed me to confirm the hostname change, else I also thought it did not work.

[dsilletti]

Interesting that even if I change the MAC address, the IP address I've got from the DHCP is different, but the hostname I see on the router is still the same esp32-XXXXXX. @me-no-dev could you please share your relevant code lines, this is in my running sketch (including the MAC address change I applied now for testing):

  WiFi.disconnect(true,true);
  delay(1000);
  WiFi.mode(WIFI_STA);
  uint8_t newMACAddress[] = {0x32, 0xAE, 0xA4, 0x07, 0x0D, 0x66};
  esp_wifi_set_mac(WIFI_IF_STA, &newMACAddress[0]);
  esp_wifi_set_country_code("IT", true);
  WiFi.setHostname("hostname");

[gonzabrusco]

Apparently WiFi.setHostname should be called before setting WiFi.mode in order to work.

[dsilletti]

Thank you @gonzabrusco it works!
Calling WiFi.setHostname before WiFi.mode solved the issue.

 WiFi.disconnect(true,true);
 delay(1000);
 WiFi.setHostname("hostname");
 WiFi.mode(WIFI_STA);  

[Xylopyrographer]

Wouldn't it be super if the all the WiFi call setting sequences were documented somewhere... 😉