## Describe the bug
I tried to run the N3IWF on free5GC, however it doesn't start. When I run the TestNon3GPP, the test passes (logs attached on trace file section). When I start free5GC with the N3IWF (both with the default config or after following the instructions from [here](https://free5gc.org/guide/n3iwue-installation/) ), then it fails to load N3IWF with the error "[ERRO][N3IWF][NGAP] [SCTP] DialSCTP(): connection refused"

## To Reproduce
Steps to reproduce the behavior:
1. Clone  and install free5GC
2. Start the `run.sh` script with `-n3iwf` parameter
3. N3IWF can't start

## Expected behavior
free5GC and N3IWF load correctly.

## Screenshots

![image](https://github.com/free5gc/free5gc/assets/25849028/87ddad00-4def-4862-8bd7-d1c3ba5634ef)


## Environment:
 - free5GC Version: v3.4.0*
 - OS: Ubuntu Server 20.04.6
 - Kernel version: 5.4.0-173-generic
 - go version: go1.21.6 linux/amd64
 - c compiler version (Option): gcc (Ubuntu 9.4.0-1ubuntu1~20.04.2) 9.4.0

\* I also have tried with nightly (commit https://github.com/free5gc/free5gc/commit/8bfdd817c44fd1342accb6e7af5f73a5f0edc223) too with the same result

## Trace File
### Configuration File
[free5gc-config.zip](https://github.com/free5gc/free5gc/files/14601425/free5gc-config.zip)

### PCAP File
[free5gc.pcap.zip](https://github.com/free5gc/free5gc/files/14601351/free5gc.pcap.zip)

### Log File
[free5gc.log](https://github.com/free5gc/free5gc/files/14601103/free5gc.log)

[free5gc-TestNon3GPP-log.txt](https://github.com/free5gc/free5gc/files/14601470/free5gc-TestNon3GPP-log.txt)

The N3IWF slice of the `free5gc.log` file is below:
```
2024-03-13T23:46:42.716519029Z [INFO][N3IWF][Main] N3IWF version:  
	free5GC version: v3.4.0-17-g8bfdd81
	build time:      2024-03-13T21:15:35Z
	commit hash:     a4088a87
	commit time:     2023-12-19T09:23:50Z
	go version:      go1.21.6 linux/amd64
2024-03-13T23:46:42.716575719Z [INFO][N3IWF][CFG] Read config from [./config/n3iwfcfg.yaml]
2024-03-13T23:46:42.717434421Z [INFO][N3IWF][Main] Log enable is set to [true]
2024-03-13T23:46:42.717449811Z [INFO][N3IWF][Main] Log level is set to [info]
2024-03-13T23:46:42.717461991Z [INFO][N3IWF][Main] Report Caller is set to [false]
2024-03-13T23:46:42.717469251Z [INFO][N3IWF][Init] Server started
2024-03-13T23:46:42.717647921Z [WARN][N3IWF][CTX] Parse PKCS8 private key failed: x509: failed to parse private key (use ParsePKCS1PrivateKey instead for this key format)
2024-03-13T23:46:42.717669251Z [INFO][N3IWF][CTX] Parse using PKCS1...
2024-03-13T23:46:42.741264847Z [WARN][N3IWF][Init] netlink.RouteAdd: file exists
2024-03-13T23:46:42.741299217Z [INFO][N3IWF][Init] Setup XFRM interface xfrmi-default
2024-03-13T23:46:42.742817060Z [ERRO][N3IWF][NGAP] [SCTP] DialSCTP(): connection refused
2024-03-13T23:46:42.742880450Z [INFO][N3IWF][NGAP] Retry to connect AMF after 1 second...
2024-03-13T23:46:43.744089769Z [ERRO][N3IWF][NGAP] [SCTP] DialSCTP(): connection refused
2024-03-13T23:46:43.744122919Z [INFO][N3IWF][NGAP] Retry to connect AMF after 1 second...
2024-03-13T23:46:44.777509353Z [ERRO][N3IWF][NGAP] [SCTP] DialSCTP(): connection refused
2024-03-13T23:46:44.777553264Z [INFO][N3IWF][NGAP] NGAP receiver stopped
2024-03-13T23:46:44.777562624Z [ERRO][N3IWF][NGAP] Failed to connect to AMF.
2024-03-13T23:46:44.777572284Z [ERRO][N3IWF][Init] Start NGAP service failed: NGAP service run failed
```

## System architecture (Option)

VM running on Oracle Virtual Box

free5GC's VM has a fixed IP (10.0.0.110)

## Additional context
I tried to change `Nwu interfaces parameters` and the `GTPBindAddress` IP but without success. I've also tried to run my setup on another local network address (172.16.x.x) to avoid IP conflicts and I get the same error.

Another thing I tried was to run N3IWF after the other NFs (as suggested [here](https://forum.free5gc.org/t/n3iwf-connection-to-amf-fails/1337) ) to make sure AMF is already running when N3IWF starts. This [other post](https://forum.free5gc.org/t/testnon3gpp-network-interface-help/2164/7) suggested to use the recommended software (Ubuntu 20.04 and kernel 5.4.x) which is what I'm currently using (see screenshot above)

PS: I didn't post my issue on free5GC forum because I couldn't get the confirmation mail (is protonmail blocked there?)

TIA, Leo.

[Bugs] N3IWUE fails to stablish network connection with N3IWF in v3.4.0
This is a GitHub Issue
repo:free5gc
owner:free5gc
Title : [Bugs] N3IWUE fails to stablish network connection with N3IWF in v3.4.0
Issue date:

--- start body ---
## Describe the bug
I tried to run the N3IWF on free5GC, however it doesn't start. When I run the TestNon3GPP, the test passes (logs attached on trace file section). When I start free5GC with the N3IWF (both with the default config or after following the instructions from [here](https://free5gc.org/guide/n3iwue-installation/) ), then it fails to load N3IWF with the error "[ERRO][N3IWF][NGAP] [SCTP] DialSCTP(): connection refused"

## To Reproduce
Steps to reproduce the behavior:
1. Clone  and install free5GC
2. Start the `run.sh` script with `-n3iwf` parameter
3. N3IWF can't start

## Expected behavior
free5GC and N3IWF load correctly.

## Screenshots

![image](https://github.com/free5gc/free5gc/assets/25849028/87ddad00-4def-4862-8bd7-d1c3ba5634ef)


## Environment:
 - free5GC Version: v3.4.0*
 - OS: Ubuntu Server 20.04.6
 - Kernel version: 5.4.0-173-generic
 - go version: go1.21.6 linux/amd64
 - c compiler version (Option): gcc (Ubuntu 9.4.0-1ubuntu1~20.04.2) 9.4.0

\* I also have tried with nightly (commit https://github.com/free5gc/free5gc/commit/8bfdd817c44fd1342accb6e7af5f73a5f0edc223) too with the same result

## Trace File
### Configuration File
[free5gc-config.zip](https://github.com/free5gc/free5gc/files/14601425/free5gc-config.zip)

### PCAP File
[free5gc.pcap.zip](https://github.com/free5gc/free5gc/files/14601351/free5gc.pcap.zip)

### Log File
[free5gc.log](https://github.com/free5gc/free5gc/files/14601103/free5gc.log)

[free5gc-TestNon3GPP-log.txt](https://github.com/free5gc/free5gc/files/14601470/free5gc-TestNon3GPP-log.txt)

The N3IWF slice of the `free5gc.log` file is below:
```
2024-03-13T23:46:42.716519029Z [INFO][N3IWF][Main] N3IWF version:  
	free5GC version: v3.4.0-17-g8bfdd81
	build time:      2024-03-13T21:15:35Z
	commit hash:     a4088a87
	commit time:     2023-12-19T09:23:50Z
	go version:      go1.21.6 linux/amd64
2024-03-13T23:46:42.716575719Z [INFO][N3IWF][CFG] Read config from [./config/n3iwfcfg.yaml]
2024-03-13T23:46:42.717434421Z [INFO][N3IWF][Main] Log enable is set to [true]
2024-03-13T23:46:42.717449811Z [INFO][N3IWF][Main] Log level is set to [info]
2024-03-13T23:46:42.717461991Z [INFO][N3IWF][Main] Report Caller is set to [false]
2024-03-13T23:46:42.717469251Z [INFO][N3IWF][Init] Server started
2024-03-13T23:46:42.717647921Z [WARN][N3IWF][CTX] Parse PKCS8 private key failed: x509: failed to parse private key (use ParsePKCS1PrivateKey instead for this key format)
2024-03-13T23:46:42.717669251Z [INFO][N3IWF][CTX] Parse using PKCS1...
2024-03-13T23:46:42.741264847Z [WARN][N3IWF][Init] netlink.RouteAdd: file exists
2024-03-13T23:46:42.741299217Z [INFO][N3IWF][Init] Setup XFRM interface xfrmi-default
2024-03-13T23:46:42.742817060Z [ERRO][N3IWF][NGAP] [SCTP] DialSCTP(): connection refused
2024-03-13T23:46:42.742880450Z [INFO][N3IWF][NGAP] Retry to connect AMF after 1 second...
2024-03-13T23:46:43.744089769Z [ERRO][N3IWF][NGAP] [SCTP] DialSCTP(): connection refused
2024-03-13T23:46:43.744122919Z [INFO][N3IWF][NGAP] Retry to connect AMF after 1 second...
2024-03-13T23:46:44.777509353Z [ERRO][N3IWF][NGAP] [SCTP] DialSCTP(): connection refused
2024-03-13T23:46:44.777553264Z [INFO][N3IWF][NGAP] NGAP receiver stopped
2024-03-13T23:46:44.777562624Z [ERRO][N3IWF][NGAP] Failed to connect to AMF.
2024-03-13T23:46:44.777572284Z [ERRO][N3IWF][Init] Start NGAP service failed: NGAP service run failed
```

## System architecture (Option)

VM running on Oracle Virtual Box

free5GC's VM has a fixed IP (10.0.0.110)

## Additional context
I tried to change `Nwu interfaces parameters` and the `GTPBindAddress` IP but without success. I've also tried to run my setup on another local network address (172.16.x.x) to avoid IP conflicts and I get the same error.

Another thing I tried was to run N3IWF after the other NFs (as suggested [here](https://forum.free5gc.org/t/n3iwf-connection-to-amf-fails/1337) ) to make sure AMF is already running when N3IWF starts. This [other post](https://forum.free5gc.org/t/testnon3gpp-network-interface-help/2164/7) suggested to use the recommended software (Ubuntu 20.04 and kernel 5.4.x) which is what I'm currently using (see screenshot above)

PS: I didn't post my issue on free5GC forum because I couldn't get the confirmation mail (is protonmail blocked there?)

TIA, Leo.

--- end body ---
