Raspberry Pi

Install BOINC:

Open the terminal and use the following commands:
sudo apt-get update
sudo apt-get install boinc

Allow remote access to the BOINC client:

In the terminal use the following command:
sudo pcmanfm

In the just opened file manager go to /var/lib/boinc-client
If you want to use a password open ui_rpc_auth.cfg and enter a password or leave it empty.

Right click on the file ‘remote_host.cfg‘, open with text editor and at the end of the file enter the IPv4 address (or addresses each on a new line, without any spaces or comma) of your BoincTasks computer. 
Now open ‘gui_rpc_auth.cfg‘ and enter a password. So this is a file that only contains the password, or is empty when you don’t use a password.

Restart the BOINC client:

For the changes to take effect, restart the computer or the BOINC client.
Go to the ‘Terminal’ and type ‘/etc/init.d/boinc-client restart’
The BOINC client is restarting and the changes will take effect.

Connect to BoincTasks:

In BoincTasks, select ‘Computer->Find computers‘, the address is the start of the address range of the IPv4 of the remote computer.
Click Scan address range, the remote computer should show up, if it doesn’t check, your firewall.

Select the checkbox left of the IP and MAC of the remote computer and click on ‘Add selected’.
If the IP address of the remote computer isn’t fixed or you don’t know, click on the IP Address and make it blank, so it leaves the MAC Address. The MAC Address will be used to find the IP Address of the remote computer.
You know the IP address and the remote computer IP address is static, leave the IP Address in the field, this connects slightly faster than with the MAC Address.
If needed fill in the Password or make sure to leave it blank.

Fixed IP:

BoincTasks connects a little bit quicker if you can set up a fixed IP address.
Right click on connections (upper right corner the up and down arrow).
Select Wireless & Wired Network Settings.
Choose e.g. eth0 for the wired connection.

Select Auto configure empty options and Disable IPv6.
Add the fixed IP4 Address and you are set.
Restart Raspberry Pi.