What is the problem?
Everything seems to work except the octoprint server connecting out on the internet.
I installed 2019-09-26-octopi-buster-lite-0.17.0.img on a Raspberry Pi 3. I run these from hardisks not the sd cards. This isn't difficult and I had 2 set ups running for 4 years (older versions of octopi).
I updated these using the normal apt commands.
What did you already try to solve it?
looked in the log files: this is the section with errors
I tried to paste the portion of octoprint.log here, it pasted fine but because it contains what your system considers links it won't let me create the topic. I'll try to find someway to upload the file.
editing post might let me do this. Nope, I'll just cut some out
2020-10-20 02:10:35,194 - octoprint.plugins.announcements - ERROR - Could not fetch channel _important from https://octoprint.org/feeds/important.xml: HTTPSConnectionPool(host='octoprint.org', port=443): Max retries exceeded with url: /feeds/important.xml (Caused by NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x72060ff0>: Failed to establish a new connection: [Errno -3] Temporary failure in name resolution',))
I can do most anything from the command line, I can ping all hostnames involved above (octoprint.org, plugins.octoprint.org, octoprint.plugins.announcements, ...). The online connectivity test passes with any dns nameserver I've used.
Raspberry Pi is hardwired, no wifi involved.
Logs (syslog, dmesg, ... no logs, no support)
syslog and dmesg show nothing abnormal, all failures had to do with video and webcam, not connected to a printer just yet.
Additional information about your network (Hardware you are trying to connect to, hardware you are trying to connect from, router, access point, used operating systems, ...)
I use a pfsense router, no problems with any other computer connected (there are 6 including the 1 older octoprint setup that still works.