I am trying to follow the procedure given in https://alexanderhoughton.co.uk/blog/connecting-to-raspberry-pi-direct-to-pc-via-ethernet/ - in briefly, it says:
- Raspberry Pi is already connected with a network cable from its Ethernet port to the Windows PC Ethernet port
- Set the Windows Ethernet adapter to Static IP address; the page uses 192.168.111.1 with subnet mask 255.255.255.0
- Open https://pjo2.github.io/tftpd64/, enable only DHCP Server, set its Default router to the previous 192.168.111.1, with IP Pool start address 192.168.111.10 and pool size 10, Mask again 255.255.255.0
- "After I hit OK, I waited a few moments until the Pi was automatically assigned an IP address"
The funny thing is, the first time I tried this procedure on my Windows 10 laptop, it worked immediately / "out of the box"; and I was, like, "yeah"
Then I tried it few days later, it did not work at first, then I tried scanning/capturing with Wireshark on the Windows PC (only on the Ethernet adapter), plugging/unplugging the network cable a couple of times - and eventually it started working again.
Then I try it today, and it just won't work, no matter how much I restart/unplug.
So, the problem is that the tftpd64 DHCP server does not report any DHCP activity at all, and the Raspberry Pi does not get an IP address assigned (even though I can see some activity via the Windows PC Ethernet port green and orange LEDs).
The weird thing is that, if I first start the tftpd64 DHCP server, wait for some minutes to confirm no responses, - and then I fire up Wireshark afterwards, so it runs simultaneously with the tftpd64 DHCP server - Wireshark does report DHCP DISCOVER messages/packets from a Raspberry Pi, no problem!? (and Wireshark did not even ask for Elevation/Administrative privileges via User Access Control / UAC)?
So, the problem is that these DHCP DISCOVER packets apparently never reach the tftpd64 DHCP server software; and I simply cannot find a reason why that would be the case (especially since Wireshark can see the same packets).
Windows Defender Firewall is enabled on the Windows PC - but then, I haven't disabled or changed it, since the first time I saw this procedure work. In any case, the tftpd64 entry in the Allowed apps list of Window Defender is allowed both on Private and Public networks (while the Raspberry Pi is connected, Windows reports Unidentified Network, and considers it as Guest or Public Network); in Windows Defender Firewall in Inbound Rules, tftpd64 is Allowed for all ports, both TCP and UDP. (but again, Windows Defender Firewall did not seem to interfere the first time I saw the procedure work, and I haven't changed it myself since then).
(Strangely, there is no entry for the Wireshark program in Windows Defender Firewall - possibly because it uses its own drivers to capture network traffic ?!)
So, my question is - what could possibly be the reason, that DHCP DISCOVER packets reaching this Windows 10 PC (confirmed as visible in Wireshark), do not propagate to software like tftpd64? How on Earth would I even start debugging this kind of a problem? And what options do I have to fixing this issue?
(Not being a network expert, when I have similar (though in retrospect, easier) network problems, I usually just fire up Wireshark, and eventually track an error down in its logs; but in this case, Wireshark reports everything is OK, and packets I expect indeed reach the Windows PC -- while the tftpd64 does not see and does not react to these packets?)
