I see your attachments and and I can see two things.
This is to connect with your VPN of your red mobile , I can see that quite fails, that means it's a little unstable
Second: Check this
POST /api/v1.6/variables/5408256b76254210e3acafbf/values HTTP/1.1
That error is because you begin to communicate without good connection to the ubidots server. When you use AT+CIPSTART="tcp","things.ubidots.com","80" you'll need to wait until you CONNECT OK reply.
Then you need more delay.