[ADTech]

The test on your remote where you punched in "35" and it tuned to 7.1 indicates you're tuned into the UHF channel which, unfortunately is a 15 kW low-power UHF which limits it's ability to penetrate to impaired locations. The TV set performs the translation if the relationship was programmed in during the auto-program. This does not apply to the NBC station, different logic applies for it. Some tuners, in their diagnostic screen, will explicitly identify the operating frequency which would be definitive.

Is my hunch regarding your surroundings correct? If so, I've offered my best advice already. Unless someone else has additional ideas, your reception is what it is due to your surroundings.