anfedoro created an issue (kamailio/kamailio#4344)

Hello please advice what is wrong The scenario is following

Client get registred with p-cscf using udp as transport and ipsec enabled Registration completed successfully. Client send reg event SUBSCRIBE, and get 200 back But it do not get any notification then. In p-cscf container I am observing NOTIFY coming from s-cscf and then something strange happen

``` 52(95) NOTICE: {1 350779919 NOTIFY 0ed4dd8c-89a5-42ac-80cb-690891a400f1} <script>: PCSCF: NOTIFY sip:172.22.0.1:55822;transport=udp (sip:9076543210@ims.mnc001.mcc001.3gppnetwork.org (172.22.0.20:6060) to sip:9076543210@ims.mnc001.mcc001.3gppnetwork.org, 0ed4dd8c-89a5-42ac-80cb-690891a400f1) 52(95) NOTICE: {1 350779919 NOTIFY 0ed4dd8c-89a5-42ac-80cb-690891a400f1} <script>: Within DLG 52(95) NOTICE: {1 350779919 NOTIFY 0ed4dd8c-89a5-42ac-80cb-690891a400f1} <script>: Within loose route 52(95) NOTICE: {1 350779919 NOTIFY 0ed4dd8c-89a5-42ac-80cb-690891a400f1} <script>: PCSCF MO_indialog: Destination URI: <null> Request URI: sip:172.22.0.1:55822;transport=udp 52(95) NOTICE: {1 350779919 NOTIFY 0ed4dd8c-89a5-42ac-80cb-690891a400f1} <script>: Source IP and Port: (172.22.0.20:6060) Route-URI: sip:mo@172.22.0.21:6101;lr=on;ftag=b7f568fe 52(95) NOTICE: {1 350779919 NOTIFY 0ed4dd8c-89a5-42ac-80cb-690891a400f1} <script>: Received IP and Port: (172.22.0.21:6101) 52(95) NOTICE: {1 350779919 NOTIFY 0ed4dd8c-89a5-42ac-80cb-690891a400f1} <script>: Next hop domain: (172.22.0.1) 52(95) NOTICE: {1 350779919 NOTIFY 0ed4dd8c-89a5-42ac-80cb-690891a400f1} <script>: Contact header: sip:scscf.ims.mnc001.mcc001.3gppnetwork.org:6060 52(95) INFO: {1 350779919 NOTIFY 0ed4dd8c-89a5-42ac-80cb-690891a400f1} ims_ipsec_pcscf [cmd.c:1187]: ipsec_forward(): new destination URI: sip:172.22.0.1:55822 99(142) ERROR: <core> [core/tcp_main.c:4645]: handle_tcpconn_ev(): connect 172.22.0.1:55822 failed ```

as you may see, request states transport=udp, **Request URI: sip:172.22.0.1:55822;transport=udp** while p-cscf then trying to use tcp?? **99(142) ERROR: <core> [core/tcp_main.c:4645]: handle_tcpconn_ev(): connect 172.22.0.1:55822 failed** what is wrong?

Using tcp as a transport initially works well and NOTIFY is coming to the client.

thanks in advance