I think what might confuse you is that there is no port 23334 open/visible at the start9 host level, but the package containers themselves can show the port is listening/connected. On my start9 host, the working Datum container can see the following ports (hex ports converted to decimal so we can pick out 23334 etc)
start9@p-c:~$ start-cli package attach datum cat /proc/net/tcp* | perl -pe 'while (/:(\X\X\X\X) /) { $d=sprintf("%5d",hex $1); s/:$1 /:$d /}'
sl local_address rem_address st tx_queue rx_queue tr tm->when retrnsmt uid timeout inode
0: 00000000: 5355 00000000: 0 0A 00000000:00000000 00:00000000 00000000 996 0 17367 1 000000007135f841 100 0 0 10 5
1: 5A03000A:37434 0103000A:56287 01 00000000:00000000 00:00000000 00000000 0 0 63959069 1 00000000d3f8ce9f 20 4 30 10 -1
2: 5A03000A:39470 0103000A:56287 01 00000000:00000000 00:00000000 00000000 0 0 66522197 1 000000005a76bfdc 20 4 0 10 -1
3: 5A03000A:51448 2497CB9F:28915 01 00000000:00000000 00:00000000 00000000 0 0 57876344 1 000000004cc18c13 33 4 30 2 2
4: 0100007F:45398 0100007F: 7152 06 00000000:00000000 03:00000BD0 00000000 0 0 0 3 000000002d3c02cb
sl local_address remote_address st tx_queue rx_queue tr tm->when retrnsmt uid timeout inode
0: 00000000000000000000000000000000: 7152 00000000000000000000000000000000: 0 0A 00000000:00000000 00:00000000 00000000 0 0 57879756 1 000000004dec4d04 100 0 0 10 0
1: 00000000000000000000000000000000:23334 00000000000000000000000000000000: 0 0A 00000000:00000000 00:00000000 00000000 0 0 57876363 1 00000000f5eefe02 100 0 0 10 0
2: 00000000000000000000000000000000: 5355 00000000000000000000000000000000: 0 0A 00000000:00000000 00:00000000 00000000 996 0 17374 1 0000000061bd1e01 100 0 0 10 5
3: 0000000000000000FFFF00000100007F: 7152 0000000000000000FFFF00000100007F:35738 06 00000000:00000000 03:00000FBC 00000000 0 0 0 3 0000000060395487
4: 0000000000000000FFFF00000100007F: 7152 0000000000000000FFFF00000100007F:45388 06 00000000:00000000 03:00000BD0 00000000 0 0 0 3 00000000e140663f
5: 0000000000000000FFFF00000100007F: 7152 0000000000000000FFFF00000100007F:44514 06 00000000:00000000 03:00000006 00000000 0 0 0 3 00000000bea37b28
6: 0000000000000000FFFF00000100007F: 7152 0000000000000000FFFF00000100007F:38604 06 00000000:00000000 03:000003F7 00000000 0 0 0 3 00000000fa296808
7: 0000000000000000FFFF00000100007F: 7152 0000000000000000FFFF00000100007F:49244 06 00000000:00000000 03:000013AA 00000000 0 0 0 3 000000003717192f
8: 0000000000000000FFFF00000100007F: 7152 0000000000000000FFFF00000100007F:35726 06 00000000:00000000 03:00000FBC 00000000 0 0 0 3 00000000f3cf3f99
9: 0000000000000000FFFF00000100007F: 7152 0000000000000000FFFF00000100007F:34888 06 00000000:00000000 03:000007E4 00000000 0 0 0 3 00000000c9378e64
10: 0000000000000000FFFF00000100007F: 7152 0000000000000000FFFF00000100007F:34880 06 00000000:00000000 03:000007E4 00000000 0 0 0 3 000000004ee515af
11: 0000000000000000FFFF00000100007F: 7152 0000000000000000FFFF00000100007F:49250 06 00000000:00000000 03:000013AA 00000000 0 0 0 3 00000000e32b819b
12: 0000000000000000FFFF00005A03000A:23334 0000000000000000FFFF00001F00A8C0:62553 01 00000000:00000000 00:00000000 00000000 0 0 57878528 1 00000000db92b3f7 27 4 31 5 4
13: 0000000000000000FFFF00000100007F: 7152 0000000000000000FFFF00000100007F:44508 06 00000000:00000000 03:00000006 00000000 0 0 0 3 000000002d8a7a4f
14: 0000000000000000FFFF00000100007F: 7152 0000000000000000FFFF00000100007F:38606 06 00000000:00000000 03:000003F8 00000000 0 0 0 3 00000000e2fd715d
15: 0000000000000000FFFF00005A03000A:23334 0000000000000000FFFF00005500A8C0:52666 01 00000000:00000000 00:00000000 00000000 0 0 57878527 1 000000006c81a486 22 4 30 6 4
You can see the port 23334 listening and 2 connections to it listed. Note these are IPv6.