My laptop OpenVPN client establishes a TAP device. My client config is TUN, though. This devices shows under ifconfig /ALL with the IP

and a subnetmask of (!!!)

This subnetmask is obviously a multi client mask setup which gives only 4 IPs from the subnet to each client.

I have troubles pinging LAN clients inside and outside the tunnel on the remote LAN and suspect the multi client mask to be the reason.

How can I change the mask to a standard

More details:

I run a Synology Disk Station NAS in my home (remote) network with the IP beeing The router/standard gateway is an Ubiquity ER-X with

This NAS has an OpenVPN Server. I can connect to this server with my client on the LAN/Wifi at work (gateway; IP of my laptop in the wifi is; tunnel IP is

The tunnel gives my laptop an IP of and my remote server on the NAS has

I disabled my laptop firewall (Windows 10).

I can connect via my laptop browser to which is the web GUI of the Synology NAS Disk Managment System, a GUI of the operating system.

The weird thing: I can not ping this IP although I am connected via the browser on parallel.

  • some of the addresses don't react to ping. openvpn.net/index.php/open-source/faq/77-server/…
    – bomben
    Aug 13, 2017 at 12:23
  • Since this is for home/private use and not business use then this question is off topic. I suggest moving this question to SuperUser where it would be on topic.
    – ojs
    Aug 13, 2017 at 16:39
  • i would be fine with that.
    – bomben
    Aug 13, 2017 at 17:07

1 Answer 1


Putting topology subnet as one single line into the client configuration file will solve this (only when dev tun is used).

I found this after a discussion with some nice people here.

More details on why multi-client setup was necessary for usage with older versions of windows TAP devices can be found here.

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