I have had my 4 tuner Tablo for 4 years now and recently I started losing recordings because of pixelation. If I watch TV through Tablo it puxelizes. I go to live TV through same antenna and the signal is perfect. I also get 5 dots for all my stations on swtup.
When you say you watch live TV through the same antenna are you using Tablo’s live TV feature or hooking the antenna directly to a TV? If the latter, the problem may be the hard drive on your Tablo or the cable to the hard drive. When not recording, try watching the Tablo through Live TV on the Tablo and if it pixelates try removing the hard drive to see if the pixelation goes away, if it does you likely have a failing hard drive or bad cable. You can safely remove your hard drive during a reboot using the blue button on the back of the Tablo.
I agree with @bbaorbb, could be a bad hard drive or cable. May possibly be a weak/failing Tablo power supply too.
One thing that I ran into is that I was using an amplifier to help pull in some low-power stations, but it was making signals from the network stations too big. Digital tuners don’t like too much signal. Once I took the amplifier out of the line, the network stations were fine (but of course I lost most of the LP stations).