computers taking a long time to connect to R6220 wifi

I have a R6220 router that is giving me some problems. My Windows 10 devices take a long time (at least 2 minutes) to connect to wifi. It's annoying that I have to wait at least 2 minutes to use my computers after turning them on or waking them from standby.

When this problem occurs, there are at least 4 entries [WLAN access rejected: incorrect security] before the entry [DHCP IP: (xxx.xxx.xxx.xxx)] (I replaced the IP address with x). The MAC address in the entries match, so I know it's the same device that is rejected at first but then allowed to connect.

Any ideas on why this is happening and how it can be fixed?

Thanks