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WiFi problem, loss of DHCP/DNS when changing from one SSID to another but OK from turn on

I am having a problem with WiFi connections from my Lenovo laptop
running xubuntu 17.10.

I have a number of different WiFi sources round our rather rambling
house so the laptop has to move from one to another as I move around.

When moving to one SSID in particular it always fails to get proper
settings via DHCP, in fact it acts rather as if DHCP fails altogether.
Network Manager tells me I'm connected but the WiFi has no IP address
and thus, obviously, no functional connection.

If I turn the laptop off and power it up then it connects OK to the
same SSID. If I just reset the laptop it *doesn't* connect
successfully. Connecting to other SSIDs around the house doesn't seem
to suffer from the same problem, it's just one SSID where this
happens. (I'm pretty sure this is the case but I've not spent a very
long time checking).

I've found that if I do "nmcli off" followed by "nmcli on" (as root of
course) then I get a good connection again. Disconnecting and
reconnecting from the Network Manager applet in the panel doesn't
clear the problem though.

Does anyone have any suggestions as to what might be wrong?

Comments

Re: WiFi problem, loss of DHCP/DNS when changing from one SSID t

By silver.bullet at 02/10/2018 - 16:11

On Sat, 10 Feb 2018 19:51:00 +0000, Chris Green wrote:
While nowadays networkmanager is held in high esteem, I anyway prefer
scripts for networking over any tool. I'm not using WiFi for a Linux
device, but I did use ADSL and I'm using DHCP connections by scripts
only. Apart from this, there were and probaply still are tools
available, that in my experiences worked and perhaps still work more
reliable, than at least oldish networkmanager releases. IOW if
something should go wrong when using networkmanager, my favorite
suspect still would be networkmanager.

Re: WiFi problem, loss of DHCP/DNS when changing from one SSID t

By Chris G at 02/10/2018 - 16:03

On Sat, Feb 10, 2018 at 07:51:00PM +0000, Chris Green wrote:
Networkmanager is now in the 'disconnected' state
wlp4s0: disconnected
wlp4s0: connecting (prepare)
wlp4s0: using connection '2860n'
Networkmanager is now in the 'connecting' state
wlp4s0: connecting (need authentication)
wlp4s0: connecting (prepare)
wlp4s0: connecting (configuring)
2860n: connection profile changed
wlp4s0: connecting (getting IP configuration)
wlp4s0: connecting (checking IP connectivity)
wlp4s0: connecting (starting secondary connections)
wlp4s0: connected
Networkmanager is now in the 'connected (local only)' state

whereas for a successful connection I see:-

Networkmanager is now in the 'disconnected' state
Networkmanager is now in the 'connecting' state
wlp4s0: connecting (prepare)
wlp4s0: using connection '2820n'
wlp4s0: connecting (need authentication)
2820n: connection profile changed
wlp4s0: connecting (prepare)
wlp4s0: connecting (configuring)
wlp4s0: connecting (getting IP configuration)
wlp4s0: connecting (starting secondary connections)
wlp4s0: connected
'2820n' is now the primary connection
Networkmanager is now in the 'connected' state
Connectivity is now 'full'