[lwip-users] Problem with TCP Connect.

[antonio]

Hi All,

I am using LWIP_2.0.3 with mbedtls. The application is basic, just connects
to the server and returns the my IP. It runs fine as long as I connect to my
own server (provided with mbedtls).

However, when I try to connect to an external server (e.g: api.ipify.org  ,
www.myip.com), sometimes it connects, and more often it does not. The TCP
connection establishment  is stuck in SYN. (*Bellow I provide Wireshark
traces*)


I am using the Sockets API. 

All hints that allow me to track the issue are welcome. 

"No.","Time","Source","Destination","Protocol","Length","Info"
"768","9.353602625","172.28.49.1","172.28.49.20","ICMP","140","Echo (ping)
request  id=0x2897, seq=0/0, ttl=64 (no response found!)"
"843","10.358160899","172.28.49.1","172.28.49.20","DHCP","420","DHCP Offer   
- Transaction ID 0x69c5240a"
"844","10.359725146","172.28.49.1","172.28.49.20","DHCP","420","DHCP Offer   
- Transaction ID 0x69c5240a"
"845","10.359913832","172.28.49.1","172.28.49.20","DHCP","420","DHCP Offer   
- Transaction ID 0x69c5240a"
"848","10.370618481","172.28.49.1","172.28.49.20","DHCP","420","DHCP ACK     
- Transaction ID 0x69c5240a"
"849","10.370645466","172.28.49.1","172.28.49.20","DHCP","420","DHCP ACK     
- Transaction ID 0x69c5240a"
"850","10.371771843","172.28.49.1","172.28.49.20","DHCP","420","DHCP ACK     
- Transaction ID 0x69c5240a"
"975","11.360078293","172.28.49.20","172.28.49.1","DNS","150","Standard
query 0xbc6b A www.myip.com"
"979","11.383859541","172.28.49.1","172.28.49.20","DNS","182","Standard
query response 0xbc6b A www.myip.com A 104.31.66.68 A 104.31.67.68"
"981","11.384709792","172.28.49.20","104.31.66.68","TCP","136","60956  > 
443 [SYN] Seq=0 Win=2144 Len=0 MSS=536"
"1240","14.349354969","172.28.49.20","104.31.66.68","TCP","136","[TCP
Retransmission] 60956  >  443 [SYN] Seq=0 Win=2144 Len=0 MSS=536"
"1509","17.351303644","172.28.49.20","104.31.66.68","TCP","136","[TCP
Retransmission] 60956  >  443 [SYN] Seq=0 Win=2144 Len=0 MSS=536"
"1793","20.350957686","172.28.49.20","104.31.66.68","TCP","136","[TCP
Retransmission] 60956  >  443 [SYN] Seq=0 Win=2144 Len=0 MSS=536"
"2027","23.352701773","172.28.49.20","104.31.66.68","TCP","136","[TCP
Retransmission] 60956  >  443 [SYN] Seq=0 Win=2144 Len=0 MSS=536"
"2230","26.352702850","172.28.49.20","104.31.66.68","TCP","136","[TCP
Retransmission] 60956  >  443 [SYN] Seq=0 Win=2144 Len=0 MSS=536"
"2495","29.354814115","172.28.49.20","104.31.66.68","TCP","136","[TCP
Retransmission] 60956  >  443 [SYN] Seq=0 Win=2144 Len=0 MSS=536"



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