[strongSwan] Do I have to set MUT lower than 1422?

[JWD]

Strongswan works fine for almost 3 years.
I have upgraded strongswan to version 5.6.3 in July 6.

Last week, I can not login email server with starttls on the other side of IPSec tunnel, and can not get a web page which size bigger than 1200byte.
Finaly, I found setting MTU=1422, everything goes fine again.

Why this happen?
Do I have to set MUT lower than 1422? 





JWD
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