There's a gradual migration to newer equipment at many campgrounds, introducing 802.11AC capability on 5 GHz, alongside the older 2.4 GHz protocols.
If you connect on 2.4 GHz, which most people do, as the campground fills up, the few narrow channels used for WiFi are hopelessly overloaded by all the phones, tablets, computers, smart TVs and other devices. The channel interference and data collisions choke off any available bandwidth. And of course, the bandwidth at most parks is very limited to begin with.
I use an
Edimax BR6478AC V2 router in the RV. It has 5 modes; the one I use is WISP. At each campground, you log into the router admin panel and do a site survey; first on 5 GHz. If there's a usable signal, I connect to it. If not, I'll survey 2.4 GHz and connect on the older frequencies. All of our WiFi devices then connect to the Edimax and share whatever WiFi connection it got. This works well with Tengo Internet as the Edimax MAC address gets authenticated with a single coupon code and all your devices are on the internet. Also, you only have to make 1 connection to the internet, via the Edimax.
The point is that as campgrounds migrate to newer equipment, you'll find more and more success on 5 GHz where there are many more channels, that are wider and less susceptible to interference. And because there are fewer devices on each channel, there are far fewer data collisions screwing things up. I've been able to stream video from a number of campgrounds by connecting on 5 GHz where there's less congestion and the 802.11AC protocol supports video streaming.
The Edimax BR6478AC V2 has 4 radios: an outbound 5 GHz 802.11AC, and an outbound 2.4 GHz 802.11 B/G. It also has 2 inbound radios so your WiFi devices can connect to the Edimax using either 5 GHz or 2.4 Ghz. And the data transfer between inbound and outbound is pretty fast.
I've tried quite a few routers and this is the best I've found.