If you're a player who's grinding out Max Raid Battles, doing random trading, or just cruising around the Wild Area, you may have been affected by a server outage that happened earlier today.
There was, in fact, a server outage for Pokemon GO on November 22, from 9:51 PM the previous day to 3:28 AM Pacific Time. Players were greeted with a message in-game that mentioned internet connectivity issues/server maintenance.
Unfortunately, there isn't a way to resolve this problem personally. All anyone can do is wait for the game to come back online. There are resources that allow players to check the status of Nintendo's online servers.
The link above will tell you up-to-the-minute news on whether or not the servers are currently available right now. There's even a place to check news related to previous server outages. Here's the link for that; it's a Japanese website, but all the information is in English.
For more specific information on maintenance that's happened in the last 24 hours, check out this link. Again it's a Japanese website, but the info is in English.
For more information on the details of Sword and Shield, check out the information at the links below!