通过Pulse Secure VPN使用Remmina连接Ubuntu 22.04的xrdp服务器失败的排查与解决求助

大家好，我最近碰到了远程连接的难题，想请各位帮忙分析下：

我的环境情况是这样的：

• 学校办公电脑：运行Ubuntu 22.04，已经安装了xrdp服务
• 家里的电脑：Dell Inspiron机型，系统是Ubuntu 20.04
• 网络连接：通过Pulse Secure VPN连接到学校的SSL服务器

问题描述：当VPN成功建立连接后，我用Remmina的RDP协议尝试连接学校电脑的xrdp服务器，但连接总是失败。Remmina在终端的输出信息如下：

me@me-Inspiron:/$ remmina

Remmina plugin glibsecret (type=Secret) has registered but not yet initialized/activated. Initialization order is 2000.

Secret plugin glibsecret has been successfully initialized and will be your default secret plugin

StatusNotifier/Appindicator support: your desktop does support it and libappindicator is compiled in remmina. Good!

Running under Gnome Shell version 3.36.9

(org.remmina.Remmina:78170): Gtk-WARNING **: 09:25:20.996: gtk_menu_attach_to_widget(): menu already attached to GtkMenuItem

[09:25:27:583] [78170:78177] [INFO][com.freerdp.core] - freerdp_connect:freerdp_set_last_error_ex resetting error state

[09:25:27:583] [78170:78177] [INFO][com.freerdp.client.common.cmdline] - loading channelEx rdpdr

[09:25:27:583] [78170:78177] [INFO][com.freerdp.client.common.cmdline] - loading channelEx rdpsnd

[09:25:27:583] [78170:78177] [INFO][com.freerdp.client.common.cmdline] - loading channelEx cliprdr

[09:25:27:583] [78170:78177] [INFO][com.freerdp.client.common.cmdline] - loading channelEx drdynvc

[09:25:27:901] [78170:78177] [INFO][com.freerdp.primitives] - primitives autodetect, using optimized

[09:25:27:902] [78170:78177] [INFO][com.freerdp.core] - freerdp_tcp_is_hostname_resolvable:freerdp_set_last_error_ex resetting error state

[09:25:27:902] [78170:78177] [INFO][com.freerdp.core] - freerdp_tcp_connect:freerdp_set_last_error_ex resetting error state

[09:25:42:917] [78170:78177] [ERROR][com.freerdp.core] - freerdp_tcp_connect:freerdp_set_last_error_ex ERRCONNECT_CONNECT_FAILED [0x00020006]

[09:25:42:917] [78170:78177] [ERROR][com.freerdp.core] - failed to connect to 137.74.123.144

特别奇怪的是，用Windows电脑通过同一个VPN连接学校的xrdp服务器完全正常，没有任何问题。我想请教大家：

1. 我该怎么进一步诊断并修复这个连接失败的问题？
2. 像VNC这类其他远程控制工具，在VPN环境下会不会比RDP更稳定好用？

另外，按照@Saxtheowl的建议，我已经尝试ping了内部IP，结果如下：

me@me-Inspiron:/$ ping 10.100.102.80
PING 10.100.102.80 (10.100.102.80) 56(84) bytes of data.
64 bytes from 10.100.102.80: icmp_seq=1 ttl=64 time=0.049 ms
64 bytes from 10.100.102.80: icmp_seq=2 ttl=64 time=0.064 ms
^C
--- 10.100.102.80 ping statistics ---
9 packets transmitted, 9 received, 0% packet loss, time 8185ms
rtt min/avg/max/mdev = 0.037/0.074/0.141/0.029 ms

me@me-Inspiron:/$ ping 127.0.0.1
PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data.
64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.047 ms
64 bytes from 127.0.0.1: icmp_seq=2 ttl=64 time=0.060 ms
^C
--- 127.0.0.1 ping statistics ---
7 packets transmitted, 7 received, 0% packet loss, time 6123ms
rtt min/avg/max/mdev = 0.047/0.062/0.076/0.008 ms

我还尝试了以下操作，但问题依然没有解决：

• 直接使用freerdp命令：xfreerdp /u:remote /v:142.75.133.134:3389
• 临时关闭防火墙：sudo ufw disable

麻烦各位帮忙看看，谢谢大家！

备注：内容来源于stack exchange，提问作者hans