First NEVER EVER install any of the following types of third party apps:
• Antivirus Apps
• Cleaning Apps
• Security Apps
• VPN Apps
• Maintenance Apps
Please locate the ones you've installed and uninstall using the developers instructions. Mac OS does not require or benefit in any way by having those t types of apps installed. Mac OS is very cat like in that it is cleans itself, it stays extremely secure and requires no third party intervention! Installing these types of apps have the exact opposite effects that users want, they make Mac OS slow, appear unstable, buggy and creates odd behaviors. In return the ONLY thing they do is put money in the developers bank accounts while helping to empty yours.
After uninstalling then restart in Safe Mode and then restart normally and test. If you continue to have problem, let us know and we will advise on next steps to take.
Then unplug your modem and router from power for 2-3 minutes, then restart and test. Moving forward to keep Mac OS secure simply keep it up-to-date and restart the Mac about 1x per week.