journal-upload & journal-remote: Changing TCP port doesn't work

systemd version the issue has been seen with

CLIENT
systemd 242 (242.84-1-arch)
+PAM +AUDIT -SELINUX -IMA -APPARMOR +SMACK -SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD +IDN2 -IDN +PCRE2 default-hierarchy=hybrid

SERVER
systemd 237
+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD -IDN2 +IDN -PCRE2 default-hierarchy=hybrid

Used distribution

CLIENT
arch

SERVER
Ubuntu 1804 on AWS

Expected behaviour you didn't see

journal-upload and journal-remote working together using a non-default TCP port.

Unexpected behaviour you saw

They work together using the default port (19532) but not a different port.

With Firefox, I confirmed the default port is closed and the server is listening on the new port. This could be a documentation error, not a programming error.

Steps to reproduce the problem

CLIENT

changed /etc/systemd/journal-upload.conf:
URL=https://server/
to
URL=https://server:12345/

SERVER

created /etc/systemd/system/systemd-journal-remote.socket.d/override.conf:
[Socket]
ListenStream=
ListenStream=12345

CLIENT

Jul 28 22:16:32.202717 client systemd[1]: Started Journal Remote Upload Service.
Jul 28 22:16:32.834654 client systemd-journal-upload[328]: [89B blob data]
Jul 28 22:16:32.947118 client systemd[1]: systemd-journal-upload.service: Main process exited, code=exited, status=1/FAILURE
Jul 28 22:16:32.994406 client kernel: audit: type=1131 audit(1564373792.939:37): pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=systemd-journal-upload comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=failed'
Jul 28 22:16:32.939000 client audit[1]: SERVICE_STOP pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=systemd-journal-upload comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=failed'
Jul 28 22:16:32.947643 client systemd[1]: systemd-journal-upload.service: Failed with result 'exit-code'.

~$ systemctl status systemd-journal-upload
● systemd-journal-upload.service - Journal Remote Upload Service
   Loaded: loaded (/usr/lib/systemd/system/systemd-journal-upload.service; enabled; vendor preset: disabled)
  Drop-In: /etc/systemd/system/systemd-journal-upload.service.d
           └─override.conf
   Active: activating (auto-restart) (Result: exit-code) since Sun 2019-07-28 22:17:07 PDT; 1min 11s ago
     Docs: man:systemd-journal-upload(8)
  Process: 356 ExecStart=/usr/lib/systemd/systemd-journal-upload --save-state (code=exited, status=1/FAILURE)
 Main PID: 356 (code=exited, status=1/FAILURE)
   Status: "Shutting down..."

Jul 28 22:17:07 client systemd[1]: systemd-journal-upload.service: Failed with result 'exit-code'.

SERVER

Jul 29 04:17:26.695761 server systemd-journal-remote[1086]: microhttpd: Error: received handshake message out of context

~$ systemctl status systemd-journal-remote.socket
● systemd-journal-remote.socket - Journal Remote Sink Socket
   Loaded: loaded (/lib/systemd/system/systemd-journal-remote.socket; enabled; vendor preset: disabled)
  Drop-In: /etc/systemd/system/systemd-journal-remote.socket.d
           └─override.conf
   Active: active (running) since Mon 2019-07-29 04:08:19 UTC; 1min 50s ago
   Listen: [::]:12345 (Stream)
    Tasks: 0 (limit: 1152)
   CGroup: /system.slice/systemd-journal-remote.socket

Jul 29 04:08:19 server systemd[1]: Listening on Journal Remote Sink Socket.

Start with the journal-upload.conf URL and the systemd-journal-remote.socket override.conf described in the report, then trace the systemd-journal-upload and systemd-journal-remote entry points while reviewing the client and server logs. Done means determining whether a non-default TCP port works correctly or documenting the configuration limitation.