I NEVER use the DIS app, when possible, on any of my phones or tablet. What I do is open my browser, (Firefox, Chrome, Safari, etc.) I open any webpage like the Google Search page. Then go to the browser's Settings (not cellphone's Settings) and click on "Request DESKTOP SITE" or something worded similar to that, depending on your browser.) Then I click on my bookmark for the DIS. And it will bring up the same webpage you would see on your computer instead of the mobile version.
I actually do this for most of the webpages I surf on my phone. I hate that there is missing stuff on the mobile pages. I prefer to see what I see at home on my computer.
You can also try going directly to the DIS instead of the Google Search page. But, since you are having problems accessing the DIS, go to Google Search first.
Also, try clearing your Internet cookies first.