SSL certificate problems on RT-AC68U running Merlin. Suspect DDNS issues?

[bradetter]

I am having continual problems with a corrupted SSL certificate on an RT-AC68U running Merlin firmware 386.10.
I have been using no-ip DDNS service and a Let's Encrypt certificate.

A couple of months ago my certificate is being rejected by Chrome and Firefox browsers.
I have performed a hard reset (WPS button) and I can't get a new certificate to install.
I keep getting hung on Authorizing....
I need to get this resolved so I can try and get my OpenVPN working (again).

One suspicious log entry is repeated multiple of the following:
Mar 29 11:33:09 syslog: wlceventd_proc_event(494): eth1: Deauth_ind AC:18:26:42:0C:CD, status: 0, reason: Deauthenticated because sending station is leaving (or has left) IBSS or ESS (3), rssi:-42
Mar 29 11:33:09 syslog: wlceventd_proc_event(494): eth2: Deauth_ind 00:E0:4C:1C:BA:1C, status: 0, reason: Deauthenticated because sending station is leaving (or has left) IBSS or ESS (3), rssi:0
Mar 29 11:33:14 syslog: wlceventd_proc_event(494): eth2: Deauth_ind 4C:BC:E9:57:49:22, status: 0, reason: Deauthenticated because sending station is leaving (or has left) IBSS or ESS (3), rssi:-57