Wireguard AX86U wireguard connection dead after upgrade firmware 388.6.0 or 388.6.2

[wliu88]

AX86U firmware 388.6.0 or 388.6.2
wgm is working fine when using 388.5, according to the changelog

- NOTE: Asus reworked the way SSL certificates are handled in
24353. The automatic conversion code does not always
work properly, you might need to force your router
to re-generate its SSL certificates by toggling the
SSL mode on the DDNS page.

I think this is cause of the issue, how to "force your router to re-generate its SSL certificates"