Not sure if this is the right forum, if not I will gladly move it.
The message seems to indicate that the router cannot connect to ASUS's firmware servers when checking for new firmware. They may have disabled the firmware check servers until they figure out why so many people have had issues installing 3.0.0.4.38251939. The message reads 'The router cannot connect to ASUS server to check for the firmware. Before buying an Asus router, it would be wise to read Daniel Aleksandersen's review of the stock Asus firmware, especially the privacy issues regarding the included Trend Micro software. Follow the steps below for setting the System Time on an ASUS-RT router to synchronize with a public time server using the NTP client. Log on to the ASUS RT router’s control panel by entering the router’s default address 192.168.1.1 to the address bar of your preferred browser. In the following example, we will demonstrate how to set up port forwarding on a router made by ASUS. Enter the router’s LAN IP address into a Web browser. Simpsons road rage steam. The ASUS router’s default IP address is 192.168.1.1. Enter the administrator username and password. The default username and password for the ASUS router is. I'm having the same issue you were, and I'm running the latest ASUS firmware, 3.0.0.4.266. Skype for business for 10.10.5 version. I had the port forwarding settings set up manually in the router before I even did a repair on Anywhere Access in Server 2012 Essentials. Even so, Server says my router isn't set up properly.
I have an ASUS router setup with the OpenVPN server enabled. Using the .ovpn file I can connect the client from inside my LAN to the router without a problem. But from the outside I am unable to connect. I don't even get to see any messages in the log files about my connection attempt. So somehow it is like the connection is blocked.
I am using xxxxx.asuscomm.com to resolve the IP address of my dynamic IP. And that seems to work just fine. Going to an online port scanner and having it scan my UDP ports it does show the openvpn port to be open for the outside world.
In the log file of the failing client (windows) I see that the most basic connection attempt 'are you there' is not working.
24/11/2020, 11:48:34 Connecting to [xxxxx.asuscomm.com]:1194 (xx.xx.xx.xxx) via UDPv4
⏎24/11/2020, 11:48:42 Server poll timeout, trying next remote entry..