就說明是 TLS 適用版本的問題
解決方式
1. 升級要連線的 FortiGate 韌體版本
不過這方式比較費功夫, 過保固的機器也不一定能有 firmware 可更新
2. 更改本機的網際網路選項，啟用支援 TLS 1.0，如下圖：
The most content which tagged as "科技英文" came from the class content in "Engineering English", it was taught by Porf. Mao Qu-Wu, Dept. of Electrical Engineering, National Cheng Kung University. The others are my working experience and notes for references.
