Web Front UI on IOS 11.4 (iphone 6s , ipad mini3) not loading

The Front web UI for hass does not load on mobile device IOS 11.4 tested on iphones 6s
using safari , chrome or firefox browser on iphone and Ipad. A blue thin bar appears on top and nothing loads up. ( While the web UI works on the computer browser with no problem). The phone is connected on home LAN, local network.
Version iphone web browser
-firefox : version 12.0
-google chrome : version 66.0.3359.122
-safari : version 11
I am able to access home assistant okay on window PC but not on IOS device, not sure if I am missing something. I have reviewed the post similar to this tried updating to home assistant version 0.71 and unistalled the homeassistant app and re-installed it again but the issue still persist on iphone or ipad. Any help will be appreciated . I also have posted this issue on github.
https://github.com/home-assistant/home-assistant-polymer/issues/1266

For more details, my home assistant running on below environment.
homeassistant : version 0.71.
running on Raspberry B 2 board:
OS raspbian: version realease 2018-04-18