Here is a VERY simple, inexpensive fix for the CP4 lack of water-proofing.
I had TWO CP’4’s drown (probably) from dew rolling off my OTA during several sessions, most likely as it slewed across the meridian position – and in both situations, my CP4’s were attached to the top of the AP-1200 axis – just as the original CP3’s were. This should not be done.
I eventually discovered that he water leak access point on the CP-4 “case” is ONLY along that fairly large spaces surrounding the ETHERNET housing. It was easy to stick two business cards into the crack. Pointing this out over a year ago, AP’s only advice was NOT to position the CP4 on top of the mount. The early User Guide was then revised to add the warning that the CP4 is not waterproof, only water resistant.
Now I see you have the same problem with your CP4, even being mounted vertically to the pier side. That is good information, since I now have my replacement, THIRD CP4 - “supposedly safely” attached - to the side of my own pier, hoping any sudden rain, or dew, would simply dribble straight down, past that connector’s sides.
There are in fact TWO REMEDIES to drowned CP4’s – even without being rained upon:
Others who bought the early run of CP4’s – which still had the traditional WHITE cases, as the CP3’s did – had no water drainage corner holes, due to a production oversight, so the case gradually filled up. My early CP4 case had to be drilled, after its second drowning.
The good news is that it seems that ALL of the other connectors on the CP4 case are higher quality, bolted down tightly from behind, and their socket pins are probably high Military Grade, well-sealed, quality, so even that potential moisture access point is unlikely.
Only the ETHERNET connector is soldered to the circuit board, and is “free-standing” through the slightly oversized square panel cut-out, completely unsealed around its sides.
I would also say, that the (later production) BLACK painted CP4 cases likely do have those drilled drain holes, but may still have rubber plugs when they arrive. Hopefully, after my two disasters, AP now seals the Ethernet connector. But, if you have an earlier production run, it would be prudent to apply those two solutions, as I have done.
It should then be safe from drowning, with drain holes present, their rubber plugs removed, and with the Ethernet connector sides sealed, on a “VERTICALLY mounted” CP4.