After replacing wifi router, one penguin connects only ipv6
 

Hya

I ran into somewhat wierd situation.

SetUp
Two laptops, (Debian buster) Two different wireless setups (in different building).

Situation.
One of the routers was replaced. -> new wpa password.

What I did
Set up new wpa password.

What happened
One of the penguins works without trouble. The other one connects to the new router only ipv6, (no ipv4!!)

Problem
I have no idea where to start troubleshooting!!

Does anybody have a good idea?

thanks in advance

cheers

How abouot using these two commands to start with?

ip -4 address
and
ip -6 address

They will output a list the interfaces that do exist on the machine they ran on.

if there is a configuration issue, stuff will be missing from the commands outputs.

Hya,

Thanks, Yves

Currently, I am away from the troubled router. I will check within several days.

cheers

I am confused; which machine is the culprit? One of the 2 routers, or one of the two laptops?
I think you need to test both laptops.
ping also has options to specifically ping ipv4 or ipv6; ping6 might even be a separate application.

Hya,

I am glad that I am not the only one who got confused. :)

As the old router is kaput, I cannot check with the old one.

The laptop, which connects only IPv6, also connects only IPv6 on some other wifi setup.

It looks like that laptop is to blame. (I guess) I am sure that the laptop used to work, it is this one and I remember I used that wifi. So, system clean installed!!

I will update.

cheers

Hya

Solved!

Several apologies.
The penguin was to blame. (not router related at all.)
It was clean install, but not quite. (several settings migrated from old ones.)

Culprit was
/etc/network/interfaces

It was set up for wpa roaming, (at least so intended)
For some reason, the line "iface default inet dhcp" was commented out.
Uncommenting this line, and adjust allow-hotplug did the job. BINGO! Happy Penguin!

Confusing point was that wired network had no trouble with this wrong(?) config file.

cheers