Wierd connection issue

[BrandonStudio]

Before filing a Bug Report

Using these will ensure you get quicker support, and make this space available for code-related issues. Thank you!

• Docs Site => Troubleshooting, quickstarts, and more advanced topics.
• Discuss Forum => Our discussion forum for users and support to mutually resolve issues & suggest ideas.
• Reddit => Our subreddit, which we monitor regularly and is fairly active.
• Knowledge Base => Older wiki.

If you are having a connection issue, it's much easier to diagnose through the discussion forum or the ticket system.

If you still want to file a Bug Report

Please let us know

• What you expect to be happening.
• What is actually happening?
• Any steps to reproduce the error.
• Any relevant console output or screenshots.
• What operating system and ZeroTier version. Please try the latest ZeroTier release.

I have several devices:

Internet
├── ISP 1
│   └── LAN 1.1 (restricted)
│       └── Device A (Windows; 1.6.6)
├── ISP 2
│   └── LAN 2.1
│       └── Device B (Debian; IPv4 only (Public IP); 1.14.0)
└── ISP 3
    ├── LAN 3.1
    │   ├── Device C (Armbian; 1.14.0)
    │   └── Router D / LAN 3.1.1
    │       ├── Device E (Windows; 1.14.0)
    │       └── Device F (Windows; 1.6.6)
    └── LAN 3.2
        └── Device G (Android; 1.14.0)

Currently,

• Every device can connect to Device B and C (both X -> B/C and B/C -> X)
• Every device except B and C cannot connect to Device A (neither X -> A and A -> X)
• Device E, F, G can connect one another
• Whether F moves to LAN 3.2 or LAN 1.1, F cannot connect to A (bothway)

Note that LAN 1.1 is restricted, which blocks ICMP packets.

It is very strange, because they could connect just few months before, and I haven't change anything since then.
And it is even stranger that only Linux devices seem to be no problem