no splash on server with plymouth-theme-ubuntu-text installed

My system (Acer Aspire 5740) does not show any splash screen from plymouth at boot.

I installed Ubuntu Server, with LVM+crypto. plymouth-theme-ubuntu-text is installed. I would expect to see some splash screen, even if this is installed as a server.
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ApportVersion: 2.20.7-0ubuntu3
Architecture: amd64
BootLog: Error: [Errno 2] No such file or directory: '/var/log/boot.log'
DefaultPlymouth: Error: command ['readlink', '/etc/alternatives/default.plymouth'] failed with exit code 1:
DistroRelease: Ubuntu 17.10
InstallationDate: Installed on 2017-10-18 (0 days ago)
InstallationMedia: Ubuntu-Server 17.10 "Artful Aardvark" - Release amd64 (20171017.1)
Lsusb:
 Bus 002 Device 003: ID 064e:a103 Suyin Corp. Acer/HP Integrated Webcam [CN0314]
 Bus 002 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
 Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 001 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: Acer Aspire 5740
Package: plymouth 0.9.2-3ubuntu17
PackageArchitecture: amd64
ProcCmdLine: BOOT_IMAGE=/vmlinuz-4.13.0-16-generic root=/dev/mapper/username--vg-root ro
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.13.0-16-generic root=/dev/mapper/username--vg-root ro
ProcVersionSignature: Ubuntu 4.13.0-16.19-generic 4.13.4
Tags: artful
TextPlymouth: /usr/share/plymouth/themes/ubuntu-text/ubuntu-text.plymouth
Uname: Linux 4.13.0-16-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin lxd plugdev sambashare sudo
_MarkForUpload: True
dmi.bios.date: 11/26/2009
dmi.bios.vendor: Phoenix Technologies LTD
dmi.bios.version: V1.09
dmi.board.name: Aspire 5740
dmi.board.vendor: Acer
dmi.board.version: Rev
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: Acer
dmi.chassis.version: Rev
dmi.modalias: dmi:bvnPhoenixTechnologiesLTD:bvrV1.09:bd11/26/2009:svnAcer:pnAspire5740:pvrRev:rvnAcer:rnAspire5740:rvrRev:cvnAcer:ct10:cvrRev:
dmi.product.name: Aspire 5740
dmi.product.version: Rev
dmi.sys.vendor: Acer