Access to LAN while VPN client is running?

[Adam Funk]

On 2017-10-31, Karl Auer wrote:

> On Tue, 2017-10-31 at 09:47 +0000, Adam Funk wrote:
>> Until recently, whenever I've used my laptop on my home NAT LAN with
>> a VPN client running, I've had access to the LAN machines (e.g.,
>> ssh). Recently, that stopped --- i.e., I can't ssh or http into any
>> local machines with the laptop VPN client running.  The only thing I
>> can think of that has changed is that I switched the router functions
>> of my cable modem off and installed a PepWave router.  But I can't
>> find anything in the router configuration related to this, and the
>> LAN was accessible with the cable modem as router and with the
>> Linksys router before that (which died).  Any suggestions?

I discovered a bit later that even with the VPN client running, I
could ping & nmap the DHCP machines but not the static LAN IP
machines...

> If the only thing that changed was your router, it is unlikely that it
> has affected your VPN. If it affected your VPN at all, it would most
> likely be to stop it working altogether.
>
> Important question: With the VPN *not* running, can you access the
> local network?
...

It turns out I'd set the router configuration wrong.  I'd set the
router's own IP address to x.x.x.1 with 255.255.255.0 as the netmask,
and then set the DHCP to use range x.x.x.129 - x.x.x.254 with
255.255.255.128 as the netmask (based on a misunderstanding of the
purpose of the latter mask).  I changed the DHCP mask to 255.255.255.0
and everything works now as I'd expected.