We are assuming that you are running Ubuntu 18.04 or later as you are connecting to the Gnome Desktop. The problem you are describing is expected when you perform a manual installation (with no further actions).
To solve your issue, you have multiple options
option 1 - manually change the look'n feel within your remote session.
This post provide a step by step explanation on what you need to do. In a nutshell,
- install Tweak tool (sudo apt-get install gnome-tweak-tool)
- Open the tool, go to Extensions node, and enable the Dock bar
- Go to Appearance node and select the Theme to be used (often it's Yaru)
Option 2 - Create a login script file
Copy the code below into your Terminal console and let it execute. This will create a file called .xsessionrc. This file is kind of login script will load your desktop configuration into the remote session. After the file is created, login back to xRDP session and see if the desktop look like the one you have when logged on locally.
cat <<EOF > ~/.xsessionrc
echo export GNOME_SHELL_SESSION_MODE=ubuntu
Option 3 - Use Scripted installation
Next time, you perform a xrdp installation, you could use the script that can be found here to automate the installation and perform for you the post-configuration actions that make the desktop interface look similar when connected locally or remotely through xrdp… There is also on how to guide provided as well with the script (see [http://c-nergy.be/blog/?p=14093])2
Please note that the script is updated on a regular base, so please be sure to check if a new version of the script is available...
Hope this help
Till next time