Ubuntu <-> Android <-> Draytek 2860VPN

On the Modem

Ensure PPTP VPN Service is Enabled in the Remote Access Control Setup.
Disable all other options.

In the PPTP General Setup, select MSCHAPv2 Only, and ensure the MPPE encryption is set to 128-bit.

In the Remote Dial In User area, create a new user, selecting PPTP only.  Create a username and password here.

On the Linux PC

Check your underlying (non VPN) connection, and ensure that the MTU is set to 1500:

Click on the network manager in the systray, and select "Edit Connections".  Add a New Point-to-point Tunneling Protocol (PPTP).

Suppy the IP address, or resolvable DNS name of the Draytek Modem, and then supply the username and password you set up on the modem in the previous section.

Finally, select Advanced, and ensure MPPE is selected and set to 128 bit.

Ubuntu 18.04 Hplip Scanner Problem

Problem

Printing works on Ubuntu 18.04 fine, but after a recent update, scanning on an HP MFP277 results in a SANE I/O Error 9.

Solution

Remove HPLIP:

$ sudo apt-get purge hplip

Download HP Public Key (Optional Step):

$ /usr/bin/gpg --keyserver pgp.mit.edu --recv-keys 0xA59047B9

Download HPLIP 19.x directly from HP, rather than from Ubuntu.

$ ./hplip-3.18.8.run

And select all the default responses.  Install plugins if requested:

$ hp-plugin

Checking for network connection...Downloading plug-in from: Plugin is not accessible. Trying to download it from fallback location: [https://developers.hp.com/sites/default/files/hplip-3.19.8-plugin.run]Receiving digital keys: /usr/bin/gpg --homedir /home/steve/.hplip/.gnupg --no-permission-warning --keyserver pgp.mit.edu --recv-keys 0x4ABA2F66DBD5A95894910E0673D770CDA59047B9

If the plugin is not accessible, as shown in the above example, simply download and execute the proposed plugin run file.

$ wget https://developers.hp.com/sites/default/files/hplip-3.19.8-plugin.run$ sh ./hplip-3.19.8-plugin.run

If the plugin install fails with the following error:

Plugin installation failederror: Python gobject/dbus may be not installederror: Plug-in install failed.

Ensure that a reboot following a previous upgrade is not pending.