revert: DNS_SERVER default back to udp://1.1.1.1

10.35.99.172 is a local-environment resolver, not suitable as a
public default. On networks where public UDP DNS is unreachable,
pass DNS_SERVER explicitly at runtime.

main.py

@@ -56,7 +56,7 @@ def run(
     socks_port: int = 1080,
     socks_user: str = "",
     socks_pass: str = "",
-    dns_server: str = "udp://10.35.99.172",
+    dns_server: str = "udp://1.1.1.1",
     pick_strategy: str = "first",
     log_level: str = "info",
     config_file_path: str = "/tmp/.sub2socks.json",
@@ -159,7 +159,7 @@ def main() -> None:
         socks_port=int(os.environ.get("SOCKS_PORT", "1080")),
         socks_user=os.environ.get("SOCKS_USER", ""),
         socks_pass=os.environ.get("SOCKS_PASS", ""),
-        dns_server=os.environ.get("DNS_SERVER", "udp://10.35.99.172"),
+        dns_server=os.environ.get("DNS_SERVER", "udp://1.1.1.1"),
         pick_strategy=os.environ.get("PICK_STRATEGY", "first"),
         log_level=os.environ.get("LOG_LEVEL", "info"),
     )