Hi DJ MarcusT, I'm from Northern California and used to do a lot of weddings in the Napa area before moving to the East Bay (Danville). I'm not as familiar with the digital of the Line6 but have had a similar experience. Mine was because I did not reset the channel on my EV wireless and tried to just use my last used channel. Whenever I reset the channel at each event I have not had a dropout issue. Maybe a different channel would have worked better? I don't know if you did try different channels at the time so it's just an idea. Also, from reading the Line6 doc's it is recommended to place the receiver at tabletop height or higher.
From personal experience, I have sold my Line 6 units b/c of the crowded wifi problems and the poor 2.4 choice they ended up using for their Digital units. The high badnwith requires more direct line of sight than using lower bands, found in the analog such as 5xx
I had tons of embarrassing dropouts and all kinds of problems with my Line 6.
After going BACK to my Shure Analog units, they were far far more reliable. I work at the same venues several times a year, and always setup in the same place.
I bought the Line 6 for better sound quality, which I will admit was better, but I would rather have more consistent reliability and less drop outs.
The 300 feet claim is way over hyped. I was lucky to get 150feet, and I had to be nearly Direct line of sight.
The trick with any wireless system is to have the antenna/receiver mounted as high as possible. Never put it on the ground.