Mobile WP App Can’t find website

have you tried basic troubleshooting steps:
– deactivating ALL (yes all) plugins temporarily to see if this resolves the problem (plugin functions can interfere). If this works, re-activate them individually (one-by-one) to find the problematic plugin(s).
– switching to the unedited default Theme (Twenty Seventeen.) for a moment using the WP dashboard to rule out any theme-specific issue (theme functions can interfere like plugins).

If t-p’s troubleshooting does not solve the problem, please perform a manual update using a fresh 4.8.1 download. While rare, sometimes the automatic update process gets interrupted and the installation becomes unstable, this should fix it.

All troubleshooting steps mentioned above have been tried on two (https://badeventer.com and https://tech-lead.net) 4.8.1 WordPress websites that were updated from 4.8 without success. There is no doubt that the upgrade from 4.8 to 4.8.1 is the cause of the problem. I manage a website https://staffmedhomecare.com that is still on 4.8 and everything is working fine.

bcworkz, It is unlikely that automatic updates on 2 websites got interrupted.

If the troubleshooting steps I listed above did not help resolve the issue, then I would sugget MANUALLY updating as recommended by @bcworkz above.

Download a fresh copy of the WordPress .zip file to your computer, unzip it, and use that to copy up all files and folders EXCEPT the wp-config.php file and the /wp-content/ directory. You may need to delete the old wp-admin and wp-includes folders and files on your server before uploading the new ones. Please read the Manual Update directions first.

I updated manually but no success! After choosing self hosted site and entering the url https://tech-lead.net I’m getting: “We’re sure this is a great site but it’s not a WordPress site, so you can’t connect it to with this app” Please try it yourself and let me know what you get.
BTW, when I use secure wifi on Comcast cable connection to the internet it works fine but not on AT&T data connection maybe this is a clue?

I managed to troubleshoot and solve the problem which was in the .htaccess file. The code below was blocking xmlrpc.php to all accept for a couple of IP addresses. After deleting it the app worked as expected. Seems that activating the GOTMLS Anti-Malware plugin’s firewall adds this code to the file. Apparently deactivating the plugin doesn’t remove the code from the .htaccess file hence the problem. This is something that the plugin developers should look into solving.

<Files xmlrpc.php>
<IfModule !mod_authz_core.c>
order deny,allow
deny from all
allow from 73.71.159.78
allow from 173.201.246.1
</IfModule>
<IfModule mod_authz_core.c>
Require ip 73.71.159.78 173.201.246.1
</IfModule>
</Files>
# END GOTMLS Patch to Block XMLRPC Access