Phone unregistering after a day

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My Configuration was working perfectly as of a few weeks ago but lately my phones have been unregistering after a day and I have to restart the ATA in order to have it registered again, I disabled SIP ALG on my router and disabled firewalls on my router, I have set the Register expiration at 60 minutes , the Reregister before Expiration to 10 seconds and the SIP Registration Failure Retry Wait Time to 120 seconds as recommended by freephoneline, I have installed the latest firmware on my router and ata, what I noticed was that on the release notes for the firmware i installed on my ata it said "fixed a current disconnect problem", could this be the unregistering problem I have been talking about? My router is a LinkSys e4200 and my ATA Model is a Grandstream HT-702, Any help would be appreciated.

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----UPDATE-----

After installing the new firmware and the ATA being on for two hours and 10 minutes it just unregistered again.

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Another Thing to note, if i login to freephoneline's website and check my SIP Settings For the SIP Status it says Im connected, but on my ATA Box it says im not registered, I can still recieve incoming calls and make outgoing calls but this is only for a short amount of time till I see the sip status on the freephoneline website change to disconnected. Is there a possibility that my ATA might be bugged?

Here is the screenshot of the sip status on the freephone line website:



Here is the screenshot of what my ATA Says (Notice the not registered for port 1):

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After a good amount of time with the ATA Saying "Not Registered" and the SIP Status on the freephoneline website Saying "Connected", the status finally changed to "Disconnected" from which now I cannot receive incoming calls.