Fix for MTProto proxy connection issues for RU users (iOS/Android/Desktop on one port)

[Mekotofeuka]

Since June 4, many MTProto proxy users from RU have been facing connection issues: clients fail to connect entirely — connection hangs at the TCP handshake stage and eventually gets blocked for ~2 minutes.

Some community workarounds that appeared on June 5 partially restore connectivity, but:

• Connection takes 15–20+ seconds
• With multiple devices from the same IP (office, Wi‑Fi, NAT), they queue up and the connection time grows significantly

I've developed a server-side fix that solves both problems. It's been tested on:

• Telemt (3.4.18, the most stable version)
• MTProto.zig
• MTG
• Original MTProto Proxy
• JSMTProxy

Key improvements:

• Fast connection in <3–8 seconds, even under load (original workarounds: 10–20+ seconds)
• One port for all clients (iOS, Android, macOS, Desktop)
• Media loads at near-original speed
• One‑click installation
• No MSS manipulation required

How it works

The script applies a two‑layer SYN filtering rule that separates devices into two groups — iOS and non‑iOS — applying different limits to each:

1. iOS clients are detected by TTL+Length fingerprint and get a dedicated fast lane
2. All other devices go through a separate per‑IP rate limit (54/minute = 1.1/sec)

This prevents iOS and Android/Desktop from interfering with each other when sharing the same IP (NAT, Wi‑Fi, office networks).

The fix also:

• Uses REJECT instead of DROP, so clients get an instant response instead of waiting 3–5 seconds for a timeout
• Disables built‑in MSS/synlimit in telemt config (they're not needed and only slow things down)

https://github.com/Mekotofeuka/MTPROTO_FIX_By_MEKO