[mythtv] Weird problem with scheduling recordings on my 17.04 frontend

[roger]

On 10/02/17 15:08, Roger James wrote:
> I am currently unable to schedule recordings on my 17.04 front-end. If 
> I select a recording to schedule from either the EPG or one  of the 
> search screens. The first time I click on record this showing in the 
> sub menu it just dismisses the sub menu and acts like nothing has 
> happened. The second time I bring up the sub menu and click I get a 
> duplicate key error logged. Nothing ever appears in the upcoming 
> recordings. After I have caused this I go to my back end which is 
> running 0.28(.0). I then find I cannot login either directly on the 
> console or remotely by SSH. It appears that it logs in but cannot 
> bring up a shell. Maybe something is stealing all the cycles. If I 
> reboot the front-end then all goes back to normal.
>
> At the moment I have not got a clue what is happening. The mythbackend 
> and mysql error logs look ok. The only clue is the duplicate error in 
> the front-end log. But the recording request does not get into the table.
>
> Ideas anyone.
>
> Roger
>
Ok,

I think I have worked it out. /etc/mythtv/config.xml has an IPV4 address 
in. This works to get things started. At some point the frontend 
suddenly switches to using IPV6 link addresses to talk to the backend. 
For some reason the database has an IPV6 link local address in 
MasterServerIP but AllowLinkLocal set to zero. I do not remember ever 
setting these fields. I suspect at some point either a mythbuntu install 
or a database update has set them. Historically my backend server always 
ran with IPV6 disabled in the kernel and various other places due to 
performance problems with DNS lookups etc. I suspect when I rebuilt the 
server a while back that was all removed.

Roger