I think so too.
I thought Tailscale was bypassing all firewalls and routers.
RESOLVED!!
I knew it would be something stupid, something I did.
It turns out that the machine that was set up as a subnet was (inadvertently) logged in my guest network
Which was isolated from the regular one. Therefore, could not see any other machine on its own.
I connected it to the main network and boom!
Thanks for all the help with setting up the subnet router.
It really made the difference.
great, glad you got it sorted out!