Issues when using Gnome OpenVPN-plugin for NetworkManager. Why?

Question

openvpn

The machine is running Pop!_OS (Ubuntu clone) 19.10 with Gnome. There is a package network-manager-openvpn-gnome that allows you to enable OpenVPN connection in the graphical interface from the menu in the upper right corner of the screen.
After the connection is established, delays appear in some cases:
- Mozilla Firefox starts about 20-30 seconds
- in the terminal, when using the command with sudo, there is a delay before entering the password of 5-10 seconds.
At the same time, Chrome starts instantly (I have an NVME SSD).
When an OpenVPN connection is not established, there are no delays.
I manually registered the DNS server 1.1.1.1 in the properties of the VPN connection - it did not help (although the OpenVPN server should already register this DNS, albeit the second one).
ip r :

default via 10.25.0.1 dev tun0 proto static metric 50 
default via 192.168.206.1 dev wlp0s20f3 proto dhcp metric 600 
10.25.0.0/24 dev tun0 proto kernel scope link src 10.25.0.7 metric 50 
169.254.0.0/16 dev wlp0s20f3 scope link metric 1000 
xx.xx.xx.xx via 192.168.206.1 dev wlp0s20f3 proto static metric 600 
192.168.206.0/24 dev wlp0s20f3 proto kernel scope link src 192.168.206.58 metric 600 
192.168.206.1 dev wlp0s20f3 proto static scope link metric 600

Here 10.25.0.0 is the OpenVPN network;
192.168.206.1 - Wi-Fi network gateway;
xx.xx.xx.xx - external IP of the OpenVPN server.
It is also strange that the tracepath of the external addresses goes through 10.25.0.1 as it should, but the tracepath of the external IP of the OpenVPN server goes through 192.168.206.1 - I don't like it.
resolvectl status :

...
...
Link 4 (tun0)
      Current Scopes: DNS
DefaultRoute setting: yes
       LLMNR setting: yes
MulticastDNS setting: no
  DNSOverTLS setting: no
      DNSSEC setting: no
    DNSSEC supported: no
  Current DNS Server: 1.1.1.1
         DNS Servers: 1.1.1.1
          DNS Domain: ~.

Link 3 (wlp0s20f3)
      Current Scopes: DNS
DefaultRoute setting: yes
       LLMNR setting: yes
MulticastDNS setting: no
  DNSOverTLS setting: no
      DNSSEC setting: no
    DNSSEC supported: no
  Current DNS Server: 192.168.203.4
         DNS Servers: 192.168.203.4
                      192.168.203.5
          DNS Domain: localdomain

Accordingly, the DNS servers of the Wi-Fi network 192.168.203.4(5) are not pinged.
Please help fix the problem.
When starting the same OpenVPN connection from the command line, there are usually no delays, but it is not convenient to enter a password and keep the terminal window open.

Answer 1

Try to disable ipv6 in connection settings.