ANSWERED TransIP API

[1713502775 0]

DNS challenges not working for letsencrypt with transip api.
Even when whitelisting large ranges:

Its fine on other connections

[1713502775 0]

Since I was having some trouble with accessing some other websites. And I could access them fine from the eddie client, I went on to investigate.

What solved my problems was setting an MSS of 1412 on the LAN interface in OPNsense, and ditching all the MTU's everywhere.
API request and websites that did not work are working fine now.

Maybe someone has a use also for this information

[1713502775 0]

Just a little addendum:

After reading some more about MTU and MSS I can say the settings can be done on the Interface connected to the Wireguard VPN.
The MTU can be set to 1420 (the default for Wireguard) and MSS can be set to 1380 (1420 - 40) 
Everything keeps working fine, and it won't affect your default LAN interface.