does anyone know what this exclamation mark means beside my club?

Go to System Settings and check the memory for the game. If there is a yellow exclamation mark (!) beside the game that means that it is corrupted. Try deleting it then clearing the console cache before redownloading to see if that helps.

None of the items have an exclamation mark, no. I would assume a question mark as the icon to the left is natural for all the items under "Other devices", yes? Also, one of these "other devices" is labeled "Ethernet Controller". Would that have anything
to do with my LAN problem?

Is there a way to identify what drivers are correct for LAN, and which ones aren't, besides the exclamation mark? Is it possible a computer can lack these drivers completely?

I have question about the Rivals mode.... when one is checking times and comparing theirs to friends and club members.... what do the half circles vs the full circles mean when marking what assists you used? I ask because I don't use a single assist yet
there is almost always a full circle marking the second to last option. I don't even know what this option means. The others are self explanatory... ABS...TCS...Automatic vs Manual vs Manaul w/clutch... UNKNOWN SYMBOL.... Dirty Lap exclamation point. Anybody
know what this "unknown" marker is for?

Check your memory in the System Settings. If the game has an exclamation mark (!) beside it delete it then clear the cache and redownload it.

Please check your storage for the game. If there is a yellow exclamation mark (!) beside it then you'll need to delete it then redownload it as it is incomplete or corrupted.