(Solved) Arduino code on ESP8266 keep crashing on submitting CPM to Radmon

Not a programmer by trade but I feel like I'm slowly gaining more insight after all these years of copy pasting and asking my more gifted friends for help

Neither am I. If you like it, don't stop. Keep on chewing away at things and you will start to understand things better. Do more and you will start to become good at what you do. As for asking questions.... The most stupid question is the question that is never asked. A manager of mine in a job long gone said this to me when he started his job there: 'Ask all the questions you want, but.... 1st time is asking, 2nd time is confirming, 3rd time is taking the piss!' So do bear that in mind. But seriously, asking questions is a good thing.

One other thing is I have shielded the GM tube with a piece of aluminium pipe (properly insulated with nice 3D printed bushings), which helps with light sensitivty, but it also influences readings. Any thoughts on this? it is pretty thick aluminium (15mm pipe, 12mm internal diameter)

Yes, I know a bit about this. From your dimensions the wall will be 3mm thick. 3mm is pretty much the exact thickness to block all soft and all hard beta. Basically you are shielding your tube from all beta radiation. You may want this, or you may not. It really depends on what you are using your counter for. Personally, I would not as I would want to catch all the radiation that finds it's way to the tube, but in certain circumstances you may want to differentiate between gamma and beta, and thus using a beta shield (as you have) will exclude the beta counts. So in theory, if I wanted to know how much beta or gamma a certain source was emitting I could first measure without a beta shield and note the counts in a certain time span, then shield the tube from beta and repeat the test and note the counts. The difference will be the beta emission only in that time frame, within a margin of error. So by taking the shielded count from the unshielded count you will have your beta only count. Radiation shielding in very simple terms, a cigarette paper will block alpha, 3mm aluminium will block nearly all beta, and lead will block gamma, but the thickness of the lead is dependant upon the radioactivity of the source. It is all about slowing down the particles from the source which you are doing with your aluminium tube. It is slowing down some particles so much they don't reach your tube. This page gives some good info: https://sciencedemonstrations.fas.harvard.edu/presentations/%CE%B1-%CE%B2-%CE%B3-penetration-and-shielding

Your tube is glass, some glass tubes like the J305 are sensitive to UV light. They should be covered from light, but if wanting to detect both gamma and beta this covering should be as thin as possible but completely block light. Some black electrical tape should do the job. Try to keep it as one layer. If you need to overlap then do this at the back, or the less detecting side. That said, it won't make much difference, but the engineer in me says it is better! 

Radmon doesn't support multiple counters on one account, so you will have to create another account of you want it logging two.

I wouldn't choose gaffa tape personally, but that is simply because it is so damn sticky and trying to get it off a tube would be a little difficult. But is should work for shielding the sun light. A quick way of testing would be a cheap UV flashlight, or even maybe a regular flashlight. Just flash it at the tube and if you hear clicks in succession with the flashlight then you can pretty much assume the light is getting to the GM tube.