I have a Flint2 and I’m having issues connecting two Ubuntu computers behind lan, one is connected to LAN2 and the other is connected to LAN3. I have set static IPs for both machines and it seems dns will resolve the ip to the hostname.local address on both sides but ping and subsequently ssh fails. I’m kind of weak on networking but am I doing something wrong? I’m mostly trying to do this so I can create a 2 node kubernetes cluster over LAN versus through tailscale.
Please check your static assignments and confirm they are correct. Check the local (on your PC) firewall as well.
Maybe first start very basic 
I read you mentoin tailscale, try without it and see if that allows ping.
I think you need to allow lan inside the tailscale tunnel but i have no experience with tailscale.
Yea I did this to no avail
Yea the static assignments are correct , also no firewall on my machines I disabled ufw
I should also mention the flint is operating as a repeater, and my goal is to connect my two Ubuntu machines via lan and run each as a kubernetes node and a NAS on the lan also backing up as storage to the nodes, I checked the machines today and seems the lan isn’t working at all, if I connect to wifi , internet works fine but they still can’t ping one another, they both are wired in to the pan ports also but those connections fail to connect
Another update, I kept tailscale up on the router but thanks to @admon i went and advertised the subnet routes to the lan/wan on my Ubuntu boxes and now am able to ping/ssh over WiFi to the lan address, but still no luck with my hardwired lan, it’s not even connecting in either box
Another update, after changing one of the wlan ports to lan I am now able to connect one of the boxes via lan (???) no clue as to why that is @admon
I am not really sure what you mean by changing a WLAN port to LAN 
Was the WAN port connected to some other device than the internet modem?
No im using it as a repeater , it was originally just a wan port but i was messing around and tried it and it works on the one box ¯_(ツ)_/¯
Update: well it randomly started working I’m not sure what I did, I ran your update tailscale script I found, messed around in the openwrt settings for a while and then messed with Ubuntu’s settings, added as a static ip and then it randomly connected and then switched over to dhcp and it stuck.. for now.. but they’re both in the wan ports that I converted into lan.