My tv and sound go off intermittently. I have checked for software upgrade, rebooted modem and unplugged tv. No solution with these measures

https://www.youtube.com/watch?v=AuWhoi5--2o
It's usually because your remote batteries are low. Remotes are known to send off some weird signals when they're on the last bit of juice. Your TV could be interpreting infrared noise from your remote as an "On" command. The power button on the remote or the TV itself could be stuck. https://www.quora.com/Why-would-a-TV-turn-off-and-on-by-itself
Samsung
Try to update the software.In some cases, a software update can correct the problem. ... If the TV turns off during the software update, it could damage the TV. Updates can take up to 30 minutes depending on network speed, so if the TV is not turning off too frequently, try updating the software.
https://www.samsung.com/us/support/troubleshooting/TSG01108742/
LG:
A TV that intermittently powers on or off is usually caused by the timer setting. ... Check if the TV power cord is securely plugged into the wall outlet or the power bar. 3. Time menu options affect TVs turning on or off automatically.
https://www.lg.com/ca_en/support/product-help/CT20098005-1412238468277-intermittent-power-or-powers-off-on
SONY:
Your Sony BRAVIA KDL-46XBR9 TV may reboot due to a damaged AC power cord. In this case you can usually resolve the rebooting problem by replacing the power cord. Your Sony BRAVIA TV may also reboot because of a bad power supply in the TV. ... The BRAVIA KDL-46XBR9 may also reboot because of incorrect settings on the TV.
https://www.techwalla.com/articles/why-is-my-sony-bravia-kdl-46xbr9-rebooting

Hi Geoff, I hope I can help you with this. If you are using an accessory device (DVD, DVR) check cables to see that they are secure and if device has audio out option that it is set correctly. Also check to see that Video and Audio cables are connected to matching inputs on your set.
If you are using DVI to HDMI you will need to use a separate digital audio cable. DVI cables do not carry audio signal. After attaching the audio cable if you still do not hear sound you may need to set Digital Audio In. To do so:

1. Press Menu Button on remote.
2. Press the cursor ring down to highlight SETUP.
3. Press the cursor ring left to enter SETUP menu.
4. Press the cursor ring down to highlight SOURCE.
5. Press the cursor ring left to enter SOURCE menu.
6. Press the cursor ring down to highlight DIGITAL AUDIO IN.
7. Press the cursor ring down to select the source you want to associate Digital Audio with. HDMI 1 or HDMI 2 in this case. You might need a software update also.
   The latest software solves the issues below:
   
   1. TV (Plasma 42" and 50") will not turn ON/shut off itself and Red LED blinks 4- times. Recover if main switch on/off.
   2. 37" LCD full white screen appear when upgrade software.
   3. Some channels not available after turn ON.
   4. Delta volume changes, not remembered.
   5. Preferred channel changes, not remembered.
   6. Green or yellow static (sometime snowy) on HDMI picture.
   7. Picture and sound loss for 5 to 10 sec (green LED is still ON) and back to normal.
   8. Audio loss in all inputs and can be recovered when main switch ON and OFF.
   9. TV set turn ON by itself/ green LED light up and goes off when set is ON.
   10. Intermittent audio loss in NTSC RF channel.
   11. Crack sound with high input signal.
   12. Include the possibility to download the rating table (RRT5 capability) for digital programs.
   13. No video/ no picture with sound.
   14. Intermittent On-Screen Menu pop up by itself and can be removed by pressing the 'MENU' button.
   15. Channel information display too long.
   16. Improvement on scramble channel.
   How to check the current software version on my TV set?
   
   1. Press 'MENU' button on remote control to display the on-screen menu.
   2. Select TV MENU and press the cursor right.
   3. Select INSTALLATION and press the cursor right.
   4. Select SOFTWARE UPGRADE and press cursor right.
   5. Select CURRENT SOFTWARE INFO to display the current software version on your TV set.
   6. If the TV software version is lower than the version posted on the website means your TV set needs to be upgraded.
   7. Follow the instruction in the user manual or Firmware Upgrade Readme file on how to upgrade your software.
   Where can I find the latest software for my TV set?
   The Firmware Upgrade Software and Readme File documents can be found on the Philips support website. Refer to the SOFTWARE section.
   

Check all ur tv inputs cables connections from the back of the tv,for like AV components and or HDMI cables for losed connections or damages cables wires.If u have cable boxes,satalite boxes or telicom compannies boxes and it plug in 24/7?Yes?Unplugs,replugs those boxes and the tv also back about an hour later.For those boxes to reboot and upgraded it softwares and the tv to do a resetting itself back to the tv factory settings.Than goes into the tv menu,go to the tv Audio Settings,to do a whole resetting to all the audio settings back to the tv factory Audio Settings.These steps,will help for ur tv to have and to get it audio sound back again.

Tries cable or satalite boxes and tv unplug,replug it back like about an hour later.For the tv resetting itself back to the factory setting and those pay boxes to reboot and upgrade the their softwares.Go into the tv menu goto Audio Setting,go down do a resetting to the audio setting back to the factory setting.By doing these steps,tv audio have a great chances of returning.

Are few solutions for you:
# increase your cache size. It means the storage space where your visited web sites were saved.
# upgrade your modem.
# upgrade your Internet connection to a DSL, ADSL or satellite one.
# give a call to your Internet provider and do a modem and connection check. Maybe is not properly set up.

Tries to reset the tv back to the factory setting.Unplug the tv and the cable box too,replug it back about an hour later.Let the cable box reboot and upgrade it softwares.Go into the tv Menu.Go to the PICTURE setting.Go down to the reset,to reset the Tuner board,this will reset the the Tuner board,back to the factory setting.This should solved ur tv problems,not than,the Tuner board is defective,must be replaced.

the modem is already old and obselete try to upgrade the modem. even though the lights on your modem works. try to call ATT because they can run a line test so they can determine if the connection is good or not

I trhink you can try to upgrade the firmware of the router.
Firmware if the software of the router.
Did you try to connect it directly to the modem.
you can connect the computer directly to the modem and check whether it is working properly through the modem.
If you need to restart the modem constantly then it could be the issue with the ISP or the modem.
Click Here to know how to upgrade the firmware

shut down tv/dig box/dvd. unplug and then leave a little (cuppa time)
replug .then start up dig box then tv then dvd.sounds like in need of "reboot"

A lot of these sets have a software upgrade that can take care of intermittent power on issues, check with the LG website and see if there is noe available for your model set, I have seen this solve these problems numerous times