@Kevin_Z

Im in the same boat, I have AX93, the AX5400 Triband Wifi 6 bought it last week in Malaysia, I have verified my .ovpn so here is my setup

1. My own server, raspberry pi4 with Debian and installation of OpenVPN Server

2. I have ensured my server ciphers are not something that trips up anywhere

3. my .ovpn has standard  

client
dev tun
proto udp
remote xxx 1194
resolv-retry infinite
nobind
persist-key
persist-tun
remote-cert-tls server
cipher AES-256-CBC
verb 3

Below in that file is "ca, cert, key" all in one neat .ovpn file to be imported.

I've checked Client OpenVPN works fine, checked Android on phone works fine, only on the router when I import the file (no user) and the pass is correct, it just states "Status: Connecting" its Enabled but Connecting, and never connects. Its a VPN Client of course in the AX5400.

Its straight out of the box. Since I have managed to verify in 2 computer systems and Android it works but it just can't connect in the router, I have to assume its something to do with the router.

  @Kevin_Z 

I solved the situation by disabling IPv6

  @Federic0 Thanks for this, Im gonna go give that a try as well, been stuck at this "Connecting..." and tried everything as my reply above yours suggests, since you resolved yours with disabling IPv6 it could suggest that the router defaults to IPv6 if its ON, and your ISP is not supporting IPv6 and it may be disabled on the OpenVPN server. With that said, fingers crossed this is the issue.

  @Kevin_Z 

Turns out IPv6 was disabled, and turns out the router is AX5400 , not 7800, its the other router. 

and

both IPv6 is disabled and the latest Firmware is installed, and it still can't connect to the internet the VPN, it is the router but I can't figure out WHY.

I have ensured Trigger port 1194 is allowed in case in the NAT and I have gone over every settings, I my routing table is

    Network Destination    Subnet Mask    Gateway    Interface
    
0.0.0.0
0.0.0.0
192.168.101.1
    
WAN
192.168.0.1    
255.255.255.0
0.0.0.0
    
LAN
192.168.101.0
255.255.255.0
0.0.0.0
WAN

I have checked everything, even the private VPN server log shows no incoming entry from the router, and when I check the router system log no mention of the attempt to enable "Connect" on the vpn, this is the second time I purchase something from TP Link that has to have some implications.

I have verified through various appliances on the network they all connect fine, phones, laptops, ipads it all connects fine so its not a network issue. Why would the router not be able to go from "Connecting" to "Connected" state when importing the .ovpn, keep in mind I already tested my paid for VPN ExpressVPN .ovpn file, both are just Connecting.

Firmware Version:
1.0.12 Build 20231023 rel.42641(5553)
Hardware Version:
Archer AX73 v2.0

Firmware is the following above, any help would be appreciated here because usually after debugging for this long it is usually not something I can just resolve, Im starting to think its the router.

  @Sunshine 

1)May I know if both IPv4 and IPv6 were enabled when you had the VPN client issue on the AX55?

Yes, IPv4 and IPv6 were both enabled

2)At that time, if you use OpenVPN client software on your phone or computer directly with IPv6 as well, were you able to connect the same cyberghost VPN?

Yes, I managed to connect BUT after the problem I tested the connection (with ipv4 and ipv6 activated and cyberghost on the PC) with ipleak: my IP was not hidden. Cyberghost does not handle IPv6 

Hi

AXE75 version 1.0

Nord vpn not connecting. Tries uploading different server configuration files . No luck. Firmware: 1.1.9 build 20231115