I tried it like this too: ThingSpeak.begin(client,IPAddress(192,168,0,178), 3000); , but that didn't work either.
Then I enabled debug printing from the library, and this is the result I get (I removed the writeAPIKey):
ts::setField (field: 1 value: "0")
ts::setField (field: 2 value: "0")
ts::setField (field: 3 value: "0")
ts::setField (field: 4 value: "0")
ts::setField (field: 5 value: "0")
ts::setField (field: 6 value: "0")
ts::writeRaw (channelNumber: 3 writeAPIKey: XXXXXXXXXX postMessage: "field1=0&field2=0&field3=0&field4=0&field5=0&field6=0")
Connect to 192.168.0.178...Success.
POST "field1=0&field2=0&field3=0&field4=0&field5=0&field6=0&headers=false"
Result Code: 200
It looks like it's connecting okay, and the result code is "200" which should mean that there are no problems. But no data gets posted to the channel.
I've tried changing to a different channel with a different API key, but still it doesn't work. Everything else is working with my local installation, including reading data from multiple channels, and writing data with python. I just can't get the Arduino to post the data, with the library or without.