I logged into Sol on the Anniversary launch and took a look.
10 instances up with 75 max players.
1 instance with 73
That's over 750 people just in Sol instances.
Agreed, I believe the normal cap was 50 per instance; they increased the Cap level amount and yesterday was their best stress test on it so far. The increase worked for the Anniversary for that amount, but couldn't handle to stress yesterday. Guess that goes to show how many people were attempting to access the same space at the same time.
Admiral's log, stardate... today, since yesterday's emergency maintenance I am still unable to login, with the system disconnecting me everytime I see a list of characters to choose. Hopefully this technical error will be solved before the weekend is over. End log.