Unable to download error connecting to server

The internet connection [data transfer] is so poor. that's all,.

make sure you have enough free space.
or move apps to external SD card if your device supports one

See some answers here:
http://forums.androidcentral.com/tablet-apps/233318-error-retrieving-information-server-rpc-s-5-aec-0-a.html

RPC 7 AEC 7 RPC 7 AEC 0 GooglePlay Apps Games

Refer to this link, it may help.

Hi,
I am assuming you are getting the error when trying to access Google Play. With that in mind these pages may help with this.
Can Download From Google Play Error RPC 5 AEC 0
http://forums.androidcentral.com/google-nexus-5/433573-google-play-services-outage-rpc-s-7-aec-0-error.html

I post on behalf of HP.

Hi, from what I found it is an error related to the Google Play services. Here are a few pages I found referring to similar errors:
http://forums.androidcentral.com/google-nexus-5/433573-google-play-services-outage-rpc-s-7-aec-0-error.html

Error Message RPC 7 AEC 0 Android Forums at AndroidCentral com

I would suggest you either contact the Google Play support number or use their support forum.
https://support.google.com/googleplay/?hl=en-CA#topic=3364260

I hope this helps.
I post on behalf of HP.

1.error code table:http://www.xcardiag.com/wholesale/super-canbus-extreme-error-free-slim-hid-xenon-conversion-kit-ac-5055w.html

Try going Settings>Accounts>Google> Tap your account> Three dots in the upper right (or press menu button) "Remove Account" ... then read your account .. then if you want, clear Play store cache and data and try it

Fixing RPC:S-5:AEC-0 Google Play Store Error

The Google Play / Android Market error retrieving information from server RPC:S-5:AEC-0 error message can be a bit of a pain, the RPC:S-5:AEC-0 error just randomly appeared on my tablet after it upgraded to a newer version of Android. However this is how i managed to fix the RPC:S-5:AEC-0 error with ease.

1. Load the Settings app, click apps, then select "All"
2. Next in the all apps view find the "Google Play Store" and click on it
3. Now click "Clear Cache" (Not Data), then Force Stop.
4. Next in the same app list find "Google Service Framework"
5. Click clear data (Not Cache), then Force Stop
6. Switch off the phone or tablet and turn it back on
7. You should be able to download and update apps from the Google Play store once more.

Enjoy no more RPC:S-5:AEC-0 errors when downloading or updating apps.
Or Simply Go to settings/app.manager/all
Delete data + cache :
Google Play Store
Google Play-services
Google Services Framework
Hangouts
Market-feedback agent (important)
Then delete google-account(data/system/user/0/ fine the accounts.db file and cut and paste it somewhere else)
Restart the phone and then re-add google-account( paste your accounts.db file earlier to it's original location).
p/s~Your device need to be rooted to remove/delete google account without a factory reset.

enjoy and have a good day :)