Reading below what I see in the screenshot; the TCPShield website followed by Server out of date! and under server name Invaild hostname. Screenshot below:
Could be an internet issue, but due to the "server out of date!" message, do ensure you're on 1.15.2 and not a snapshot or something.
I am on 1.15.2 and I always make sure I am because it is required to play on the main server of ecocitycraft. I can play on other servers as usual but not ecocitycraft.
Are you using the following IP: play.ecc.eco If so, I'd highly recommend trying to clear your DNS cache. If that does not work, please try playecc1.ddns.net