WiFi connection to the Raspi

What is the problem?

Hi im having lots of problems connecting to the raspberry pi , at first I thought its because Im using home plugs to extend my internet from downstairs to upstairs (where I have my printer) but now I brought the pi downstairs and it's right beside me, connected to the router just like my laptop and phone.. when I try to connect via octopi.local or IP address, NOTHING ... then I try octo everywhere and it connects !!!!!!! so the pi's wifi is working well but I cant access it from the LAN ?!?!? I cant understand it , sometimes it works , other times not on the LAN - it's driving me crazy and I have to go up and down stairs a whole bunch (kinda defeating why I needed octoprint in the firstplace)

What did you already try to solve it?

I set the IP as a reserved IP from the router - still nothing

Im re-flashing the SD card to see if it helps

Additional information about your setup

raspberry pi 4 2gb

Note , when I log in to my router it shows that my pi is online yet octopi.local or its ip does not work .... I reflashed the octopi image , and octopi.local worked , as soon as I turned the pi off (shut down from the octoprint menu and then turned the power off) it went back to its old ways of effing with me - I rebooted and nothing .... oh also Bonjeur is installed

Use the IP-address to connect to the Pi... for some reason octopi.local doesn't always work.

Pi's don't play well with ipv6, and it always causes issues for me. Edit /boot/cmdline.txt. At the end of the line, add ipv6.disable=1 and save. Don't hit enter, as cmdline.txt has to be a single line. Reboot and all should be good