What's the meaning of "local LAN uses the extremely common subnet address"?

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mattiapv
OpenVpn Newbie
Posts: 1
Joined: Sun Nov 03, 2019 12:03 pm

What's the meaning of "local LAN uses the extremely common subnet address"?

Post by mattiapv » Sun Nov 03, 2019 12:42 pm

Hi, I have an OpenVPN running on my raspberrypi and is working good. I can connect from everywhere and I can connect to my devices at home, NAS for example.

I'm using 192.168.1.0/24 for my LAN
My router/modem is 192.168.1.1
Raspberrypi is 192.168.1.2. Is also a DNS Server using PiHole.
VPN server 10.8.0.0/24
Routing on raspberrypi:
mattia@raspberrypi:/etc/openvpn $ route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.1.1 0.0.0.0 UG 202 0 0 eth0
10.8.0.0 0.0.0.0 255.255.255.0 U 0 0 0 tun0
192.168.1.0 0.0.0.0 255.255.255.0 U 202 0 0 eth0
I'm trying to understand why using common subnet address is a problem. This is the message in the log:
NOTE: your local LAN uses the extremely common subnet address 192.168.0.x or 192.168.1.x. Be aware that this might create routing conflicts if you connect to the VPN server from public locations such as internet cafes that use the same subnet.
I've found some answers in this forum like this one but I still don't understand. Could someone show me a routing conflict using this configuration?
At only one place I can't connect to my home devices. It has 192.168.0.0/24 too. Can be this a conflict? Adding bypass-dhcp to push "redirect-gateway def1" in server.conf fixed the problem. But I don't know what bypass-dhcp is doing.
Thanks

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