It turned out that the 2.5mm plug does not fit. It must therefore be a 5.5mm x 2.1mm plug, even though some descriptions of the extension cables state that 2.5mm is suitable for the C310.

It is about the inner diameter of the plug, here there are 2.5 and 2.1mm

If you mean the mains plug, it is 5.5 mm x 8 mm. Power supply unit is included.

Unfortunately, I can't say, as the camera is not in use. I had/have difficulties connecting it to the WLAN. Although the WLAN signal is very good, no contact could be established with the camera