Page not updating when left in background on Android

[colinl]

To see the problem, open a dashboard page in Chrome on Android and open another app or apps, so that the dashboard page goes into the background. Leave it there for some time. Using another client machine, change the state of a widget, then on the android device switch back to the page left in the background. When I do this the widget state on the Android page stays at what it was previously, rather than showing the current data. Further changes from the other client are reflected. This is a serious issue. I suspect the same thing will happen if the page is left in the foreground but the device is left untouched so that the screen is blanked and is left in that state for some time, though I have not confirmed that.

If the same operation is performed with D1, then a few seconds after switching back to the page it can be seen to auto-refresh somehow, so that the data is updated. I don't know what mechanism is used to achieve that.

[Edit] I have not now confirmed that the same situation can arise if the page is left in the foreground for long enough, particularly on battery power (not charging). I suspect again that Android is trying to extend battery life by putting the page to sleep.

[Further edit] The situation can be triggered on a device connected to WiFi (whether Android or not) by switching off the WiFi for 20 seconds then restoring it.

[colinl]

I think this is likely related to issue #620

[Soiski71]

Confirmed. For me it is the HTML page that stopps refreshing the HTML ( temp sensor codes ) from time to time in Android (always on) tablet.
Found out from Node Red server that in same time freeze happens the system log shows .

Pain as can not trust readings on screen with out confirmation of manual refresh of the page.

10:11:03 SAMONE Node-RED[887]: 3 Mar 10:11:03 - [info] [ui-base:D2] Disconnected bFaAKBFddJvzUORBAAal due to ping timeout