fix: move STUN servers into their own regions #9030
Merged
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Tailscale only tries a single STUN server in each region before cancelling all other pending STUN requests and moving on. This is usually fine, but in the case of "hard NAT" tailscale needs to get responses from two STUN regions to know that the public IP is variable and it should deploy countermeasures to get direct working.
This moves the STUN nodes out of the default region and into a new region for each STUN server starting at region ID 999+1. This should allow connections behind "hard NAT" to upgrade to direct (although this will take a bit longer, about 5-30s).
Also updates the default STUN server list to include every Google STUN server so clients have a lot to pick from. On the first netcheck, only a single STUN server will be pinged. On subsequent checks, others will be pinged to check for variability.