Ok, so I was having issues with my Tab 3 dropping the signal from my modem....Android has this thin about pinging for an internet connection and since there's no internet it drops off.
So, after 2 days of digging around on the net and trying some different ROMs, here's what works on my Tab 3 SM-t217s. The new ROM is https://www.androidfilehost.com/?fid=95916177934521088 and you will also need to flash this file first https://www.androidfilehost.com/?fid=24052804347802311
You will need to download Odin3 to connect and upload the files to your Tab 3. You will also need to load up TWRP-2.6.3.0-recovery.tar This is the backup and recovery and installation software that you will need to make all of this come together.
*Download all of the software to your pc.
*Open Odin3
*Connect your Tab to PC
*Start your TAB holding the Vol. Down button and PWR at the same time. You will get a notice in the upper left of the Tab Screen showing you are in the Odin Mode.
*In Odin3 you will see that your connected to the Tab it will show com.x Un-check the auto reboot box. Click the PDA button and locate your TWRP.tar and load it up. Hit the Start button.
*When it is done loading up the file it will show RESET above the com.x bar. Now power down the tab.
*Next Power up the Tab Holding the Vol. Up button and PWR at the same time. When you get the first screen to pop up let go of the PWR button and continue holding the Vol. Up button until the TWRP screen appears.
*Now create a recovery file for your TAB.
*Once done exit and reboot.
*Transfer from your PC to Your Tab the ROM File: https://www.androidfilehost.com/?fid=95916177934521088
*Now restart your TAB in the Odin Mode (Vol. Up & PWR together)
*In Odin3 Tap the PDA Button and load up this file: https://www.androidfilehost.com/?fid=24052804347802311. Un-check the Auto Reboot box. Hit Start and upload the file to your tab.
*After that is done reboot your tab holding the VOL Up and PWR together to get into TWRP.
*In TWRP hit Install and then locate in the folder you placed the ROM software and click on it to load it up. Swipe the slider at the bottom of the screen to begin the installation.
* The software will prompt you on configuration settings as it installs...
*Once that is done reboot and you should be good to go...Oh and it takes a bit of time for it to load up for the first time and you will be asked to enter the normal info you did when you first got the TAB.
OK, I wish I could have found this info when I was trying to figure this all out...but here it is.
Good Luck,
Bob Davis