Loosing or slow service - Loosing DNS

I have been having an issue with all my u-verse services, and the symptoms are: 1. Everything starts to get really slow. Internet starts to craw, TV image starts to stop and get pixelated, and even the voice on the phone starts to break up.

I have made 2 calls  yesterday to tech support.

On the first call, I got a very nice lady, but we applied the "basic" troubleshooting steps (she checked the line, and made me reboot the gateway hold the reset button for 3 seconds), even though I told her I had done about 3 full restarts by unplugging the unit. After about 5 minutes, it seemed that everything was OK. TV was back, Internet was in the upper 30mps (wireless connection), and phone was OK. I hang up the phone, and boom, everything went down again.

On the second call, I got a guy, who seemed a little bit more knowledgeable, as soon as I told him about the simptoms, he thought right away that the problem was not on my end. After checking the line and then something else on his system, he came back saying that the problem was with a bad NIC on a service box, the one that provides service to my "area". He even gave me the address, something like 9777/9070 Kimberly Blvd. (this address is in Boca Raton - Florida). He told me that it would take from 4-8 hours for it to be repaired. This morning, I rebooted the unit again, and everything was back to normal.

Only to come home from work, and to find out that the TV was stopped, and you know the rest...

I am a computer programmer, and have been in IT for a little over 15yrs, so I know my way around logs.  By looking at the logs from the box, these lines stand out:

2015-08-27T19:13:33-04:00 L4 mcp[3221]: mcp[handle_igmpv2_leave_msg]: missing expected data rep=0x(nil) grp=0x0x43bdd8

2015-08-27T19:14:52-04:00 L3 dnsmasq[3240]: no responses from nameserver '99.99.99.153'
2015-08-27T19:14:52-04:00 L3 dnsmasq[3240]: nameserver '99.99.99.153' is now responding
2015-08-27T19:15:22-04:00 L3 dnsmasq[3240]: no responses from nameserver '99.99.99.153'
2015-08-27T19:15:22-04:00 L3 dnsmasq[3240]: nameserver '99.99.99.153' is now responding
2015-08-27T19:15:59-04:00 L3 dnsmasq[3240]: no responses from nameserver '99.99.99.153'
2015-08-27T19:16:00-04:00 L3 sdb[331]: ELAN: Port lan-1 (eth0) is DOWN
2015-08-27T19:16:02-04:00 L3 sdb[331]: ELAN: Port lan-1 is UP. (eth0) speed 100 duplex full
2015-08-27T19:18:44-04:00 L3 dnsmasq[3240]: nameserver '99.99.99.153' is now responding
2015-08-27T19:19:15-04:00 L3 dnsmasq[3240]: no responses from nameserver '99.99.99.53'
 

Unfortunatelly, I did not save the log from when everything was down, this is from after I rebooted the unit. I told the tech support guy last night about this, but apparently he thought this was related to the problem with the NIC from the service box (if there was the problem with that). When it goes down again, I will post more from the log.

The reason for me to write this post, is that I found this other post: https://forums.att.com/t5/Residential-Wi-Fi-Gateway/RG-Keeps-loosing-DNS/td-p/4150324 and thought that it would be a good idea to share my experiences, in case someone else is experiencing this problem, and also, to hopefully, get someone with a little bit more knowledge from U-Verse to look at my case and help me get this resolved.

BTW, I have the Motorola NVG589.

EDITS:

1. It seems that everything comes back up after I reboot (hold power button 3 seconds) the gateway

I would really appreciate any help.

Thanks!

Alex