sir,why a test used 20 seconds?can it be faster?

[introspection3]

sir,why a test used 20 seconds?can it be faster?
NAT Type: Port restricted NAT
External IP Family: 1
External IP: 121.7.13.88
External Port: 10065
Time taken: 22.4233083

[xlch88]

No. Port restricted NAT is the result of several detection timeouts, and this time is uncontrollable.

You can see the specific process at stun/discover.go

// Follow RFC 3489 and RFC 5389.
// Figure 2: Flow for type discovery process (from RFC 3489).
//                        +--------+
//                        |  Test  |
//                        |   I    |
//                        +--------+
//                             |
//                             |
//                             V
//                            /\              /\
//                         N /  \ Y          /  \ Y             +--------+
//          UDP     <-------/Resp\--------->/ IP \------------->|  Test  |
//          Blocked         \ ?  /          \Same/              |   II   |
//                           \  /            \? /               +--------+
//                            \/              \/                    |
//                                             | N                  |
//                                             |                    V
//                                             V                    /\
//                                         +--------+  Sym.      N /  \
//                                         |  Test  |  UDP    <---/Resp\
//                                         |   II   |  Firewall   \ ?  /
//                                         +--------+              \  /
//                                             |                    \/
//                                             V                     |Y
//                  /\                         /\                    |
//   Symmetric  N  /  \       +--------+   N  /  \                   V
//      NAT  <--- / IP \<-----|  Test  |<--- /Resp\               Open
//                \Same/      |   I    |     \ ?  /               Internet
//                 \? /       +--------+      \  /
//                  \/                         \/
//                  |Y                          |Y
//                  |                           |
//                  |                           V
//                  |                           Full
//                  |                           Cone
//                  V              /\
//              +--------+        /  \ Y
//              |  Test  |------>/Resp\---->Restricted
//              |   III  |       \ ?  /
//              +--------+        \  /
//                                 \/
//                                  |N
//                                  |       Port
//                                  +------>Restricted

[introspection3]

dear sir,but NatTypeTester is ok(about five seconds)