The uploaded summary document has errors about the direct Ethernet connection between the Pacamara and the USB Ethernet adaptor connected to your Mac. I suspect that this misunderstanding is why you were experiencing connection issues and "strange" networking failures.
TL;DR: The recommended way to set up the Mac's Ethernet settings when directly connected to the Pacamara is to leave IP4 using DHCP, and importantly, set IPv6 to Link-Local Only. Manually setting the Mac to a static IP4 address should be avoided as it can cause intermittent connections and subtle failures. If the Mac and Pacamara are connected to a switch or router that has DHCP service then set the IPv6 to Automatic.
The first, and most important point, is that the Pacamara does not have a way to assign a static IP address. At least it did not the last time I checked. It gets it IP4 and IPv6 addresses automatically through DHCP, and if that fails, it self-assigns its IP addresses.
When you connect the Pacamara directly using Ethernet the Pacamara will first try to assign its IP addresses using the DHCP protocol. When it is unable to locate a DHCP server it will then "self assign" and IP4 and IPv6 address in the special "link local" IP range. This is a network standard that is reserved for this situation. The IP4 range is 169.254.00.00 tp 169.254.254.254. The IPv6 range is fe80::/10. IP4 self assigned addresses are randomly chosen and then checked for a collision and reassigned if one is detected. IPv6 self assigned IP addresses are static as they are derived from the Ethernet interface's MAC address.
Likewise a macOS Ethernet interface that is set up for DHCP will self-assign when no DHCP server is available on that interface's network. Even if the Wi-Fi or another Ethernet interface has access to a DHCP server the interface without will self-assign. The process of self-assigning an IP4 address on macOS can be a long process, sometimes exceeding 60 seconds, so patience is necessary to properly troubleshoot; IPv6 is practically instantaneous if limited to link-local-only.
If you assign a static IP4 address to the Mac's Ethernet port that is not in the same subnet as the Pacamara then they cannot connect using IP4, but will try none the less. For example, if you manually assign the Mac to 192.168.1.2, and the Pacamara, because it is self assigned, has 169.254.XX.XX, then a connection cannot be established. However as long as the Mac's IPv6 address has be automatically assigned (it will be a link-local address) the Pacamara and Mac will eventually connect using IPv6.
The mismatch between the IP4 addresses though can cause intermittent problems depending on how macOS and the Pacamara networking stacks work. So best practice is to avoid the mismatch.
[Note: some older Q&As discuss manually setting the Mac's IP4 address with an arbitrary one from the link-local address range. This was a work around for macOS's slow IP assignment procedure. It was a necessary before IPv6 was supported in the Pacarana's OS. The Pacarana and Pacamara now support IPv6]