@clackey, I think this is similar to what I've seen. Sometimes, and it seems mostly random, the site will not load on one device vs. another. I've had it load on my laptop but not on my desktop even when both are on the same network. I've seen it across different networks as well. It's random and mostly doesn't happen but definitely worth looking into as it seems similar to what others are reporting here. Whatever blocks it on particular machines seems to hold for a period of hours and then it will change and work again. It's strange. Haven't come across it elsewhere.
I've had the same problem consistently with my iPhone under AT&T. The site and app loads fine when using wifi, but never works when using cellular. What is odd is that the site and app works fine when using my AT&T iPad Air on cellular
Try running some SpeedTest app on the phone/tablet for the WiFi and the Cellular both and compare.
Mine is often the reverse where the WiFi will often not connect, even to Google Play too, but if I shut off the WiFi and resort to Cellular it connects fast and picks back up. The SpeedTest shows my WiFi is in the mud and 10-50 times slower than my Cellular connection which always connects and is far faster, but I have two cell towers maybe 200 yards away too and one is some major generator powered repeater with dishes. My WiFi is some copper wire buried in the dirt thing by AT&T DSL and the RF signal on the wires often gets shorted to ground when the ground gets wet - or so says their tech. Plus the AT&T wiring is too far from their hub and the RF signal degrades beyond the two miles to the thing.
My problem is slightly different, after two or three weeks of using the site, it completely fails to load. In Wi-Fi or cellular.And just freezes while loading. Once I clear the history, my cookies, and the cache, it works again. Is the only site out of about 15 I frequent that does this.
I'm T-Mobile, and I was trying to access this site this last Tuesday while waiting for my wife at the dentist's office. I thought it may have had something to do with cookies so I deleted them all. Even after that and restarting Safari on my iPhone 6S, still no phantompilots.com.