(me again) i’m trying to use both WIFI-AP, DO and SPI. But my wifi is not properly working when i let everything run at maximum (required) speed. TLDR; Seems that pins D1 and D2 interfere with WIFI, but why? i have a NodeMCU ESP8266 V3 ‘wemos’ variant. (it doesn’t have the ESP-12E board integrated) https://makerselectronics.com/product/wemos-nodemcu-v3-esp8266-340g-wifi-module-with-extra-memory-32m-flash [https://makerselectronics.com/product/wemos-nodemcu-v3-esp8266-340g-wifi-module-with-extra-memory-32m-flash] in setup() i have WiFi.softAP(ssid, password); IPAddress myIP = WiFi.softAPIP(); Serial.print("AP IP address: "); Serial.println(myIP); server.on("/", handleRoot); server.on("/set_config", handleForm); server.onNotFound(handleNotFound); server.begin(); .. t=D1;pinMode(t, OUTPUT); digitalWrite(t, LOW); t=D2;pinMode(t, OUTPUT); digitalWrite(t, LOW); t=D3;pinMode(t, OUTPUT); digitalWrite(t, LOW); What i’m seeing; if i have a main loop() with only - while (Serial.available()){ … } - server.handleClient(); Then i can see the AccessPoint and i can connect to it with my Android phone. When i add code running once every 100 msec - Debug setting set to MAX debug info to Serial - using pins D1,D2,D3 for output (to LED screen) - using D5,D7 for SPI, (to LED screen) - having SPISettings(15000000, MSBFIRST, SPI_MODE0) - taking total 60 up to 74 microseconds Then i do see the WIFI AP, and i CAN connect with the WIFI AccessPoint. (But my LED display is flickering) When i change the code to running once every 10 msec - // same as before Then i CAN connect with the WIFI AccessPoint (But my LED display is flickering) When i change the code to running once every 10 msec - Debug setting off - using pins D1,D2,D3 for output - using D5,D7 for SPI - taking total 60 up to 74 microseconds Then i CAN connect with the WIFI AccessPoint (But my LED display is flickering) When i change the code to running once every 1 msec - Debug setting None + Debug to serial - using pins D1,D2,D3 for output - using D5,D7 for SPI - taking total 60 up to 74 microseconds Then i do see the WIFI AP, but i CAN’T connect with the WIFI AccessPoint (But my LED display is showing a steady picture) When i change the code to running once every 1 msec - Debug setting None + Debug disabled - using pins D1,D2,D3 for output - NOT using D5,D7 for SPI - taking total 30 up to 40 microseconds Then i do NOT see the WIFI AP?! When i change the code to running once every 1 msec - Debug setting None + Debug disabled - NOT using pins D1,D2,D3 for output - using D5,D7 for SPI - taking total 50 up to 70 microseconds Then i CAN connect with the WIFI AccessPoint?! Seems one of the pins D1,D2,D3 is interfering with WIFI… instead of using D1,D2,D3, i changed all I/O to only use D1. Then the WIFI AP does not show up in the WIFI networks. instead of using D1,D2,D3, i changed all I/O to only use D2. Then the WIFI AP does not show up in the WIFI networks. instead of using D1,D2,D3, i changed all I/O to only use D3. Then the WIFI AP does show up in the WIFI networks. And i can connect to it. So my question is; Seems that pins D1 and D2 interfere with WIFI, but why?