Help with connection drops, interpretation log and statistics

I use a router with a 5 GHz wireless client als wan connection to a hotspot/ap of a wireless ISP.
I use non-DFS channel 48.
I have frequent connection drops with a Ubiquiti Nanobeam M5 als wireless client router.
Worse is that the router does not a autoconnect, so a manual power off/on was needed.

I replaced the router with a Linksys WRT1900acs OpenWRT router with the same configuration.
This router has the same problem but the OpenWRT router does a auto reconnect.
But the autoconnect is after 4 hours or after 5 minutes. I don't understand why this delay.
I have configured Watchcat to reboot after 15 minutes connection loss to see if this helps.

After all I don't understand the cause of he connection loss.
I have studied the logs and the LUCI statistics but I have unsufficient knowlegde to understand the monitor data. Can somebody help me to understand the possible cause and help by reading the monitor data/log.

Here you can see the loss starts at about 21:10 and reconnect at 01:27.
In the log there are records "ieee80211 phy0: change: 0x100, 0x40 and 0x60.
What does these codes mean?

Asking for help to find the cause of the instability.