Starlink will not fix that - that’s a networking issue which is not addressed by the upgrade. When you encounter that, go by the door or as one customer did, prop the door open. The steel doors and Wi-Fi signals don’t get along well (the Wi-Fi access points are typically in the hallway on older ships).
The barcode likely does contain the assignment then. It's a bit of work but you can also decode the barcode on a PC - upload the pic of the barcode (use snip) to OnLine Barcode Decoder (online-barcode-reader.com)
You can drop off luggage quite early. Pick the same time for everyone - should not be a problem getting in line with an earlier time if you show up later.
Doesn't matter what any tells you even today - tomorrow it might not be there, it even could be different in different cabins. If you need/want something like that, don't rely on RCI providing it.
One of the points of Dynamic Dining and the design/size of the "MDR" on Q class (smaller in relation to the number of passengers than other ships) was the ability to do that. Getting those early traditional diners out of there earlier, may help with MTD seating.
Ships have their own built in cell tower which is activated when far enough away from land-based coverage. Your phone will connect to that tower, though your wallet might not like the result.
Those over 7 years old used to be read only, but that restriction may have been lifted.
Biker, who puts in the resurrection meme in every year+ old thread seen to try to make it more obvious.