几分钟后，vncserver 对键盘和鼠标无响应，但屏幕仍在更新

Question

18.04 LTS 上一切运行正常。我前段时间升级了系统，但开始遇到 vnc 问题。随着屏幕内容的变化，显示将继续更新，但几分钟后我的鼠标和键盘输入会被忽略。我连接到其他主机没有问题，所以这不是我的客户端。以下是一些支持信息：

/etc/X11/Xvnc-session：

#!/bin/sh

#x-terminal-emulator -geometry 80x24+10+10 -ls -title "$VNCDESKTOP Desktop" &

# Fix to make GNOME and GTK stuff work
export XKL_XMODMAP_DISABLE=1
unset SESSION_MANAGER
unset DBUS_SESSION_BUS_ADDRESS

# exec /etc/X11/xinit/xinitrc
xrdb $HOME/.Xresources
xsetroot -solid grey

xfce4-session &

# before Ubuntu 18.04:
# gnome-settings-daemon &

# Ubuntu 18.04 and later:
/usr/lib/gnome-settings-daemon/gsd-xsettings &

。

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 20.04.2 LTS
Release:    20.04
Codename:   focal

$ vncserver -version
Couldn't start Xtightvnc; trying default font path.
Please set correct fontPath in the vncserver script.
Couldn't start Xtightvnc process.

Xvnc version TightVNC-1.3.10
Xvnc version TightVNC-1.3.10