Nested if Condition Not working while using switch

OK, so can you try using this, I've just adjusted the spacing to make things clearer and added appropriate logging, plus a final else to catch any cases that don't match your test expressions;

switch [IP::client_addr] {
 192.168.100.1 { if ([TCP::local_port] >= 5566) && ([TCP::local_port] <= 5580) } {
                  node 172.16.100.1
                  snat 10.0.0.10
                  log local0. "Client 192.168.100.1 used a port between 5566 and 5580"
               } elseif { [TCP::local_port] == 4412 } {
                  node 172.16.200.20
                  snat 10.0.0.10
                  log local0. "Client 192.168.100.1 used port 4412"
               } elseif { [TCP::local_port] == 5000 } {
                  node 172.16.100.5
                  snat 10.0.0.10
                  log local0. "Client 192.168.100.1 used port 5000"
               } else {
                  log local0. "Client 192.168.100.1 didn't use a port we tested for"
               }
                         }