Strange LAN network problem - can't "see" just one address on LAN

[Chris Green]

On Sat, Feb 12, 2022 at 11:50:55AM +0000, Colin Law wrote:
> On Sat, 12 Feb 2022 at 11:47, Chris Green <cl at isbd.net> wrote:
> >
> > Recently I have been trying out some changes to how the DHCP/DNS is
> > managed and, for some strange reason, my desktop machine at
> > 192.168.1.3 could no longer 'see' the router at 192.168.1.1.
> 
> Start by re-booting the router if you have not already done so.
> Sometimes they get confused.
> 
Good advice, it was the router causing the problem though it wasn't
that it needed a reboot.  

I found that *any* system at 192.168.1.3 couldn't access the router at
192.168.1.1.  This made diagnosis much easier because I could
configure an unimportant system (as opposed to my mail/ssh server
desktop) at 192.168.1.3 and try things.

I searched through the router's settings (Draytek Vigor 2860n so there
are a *lot* of settings) and I found a 'static route' I'd set while
trying to get something else to work.  That static router referred to
192.168.1.3 and was why I was getting my strange problem.  I've
cleared the setting and all is well now.

Phew! :-)

-- 
Chris Green