[Frakko]

I recently bought the VPN of surfshark and I configured the parameters of the router.
Would you like tips to optimize performance and security
I attach the screenshots of my configuration.
Thanks in advance

[egc]

Thanks for your contribution it is appreciated.

Unfortunately you were posting in the wrong forum.
No problem as I will move this post to the appropriate (Advanced Networking) forum.

See the forum guidelines with helpful pointers about how to research your router, where and what firmware to download, where and how to post and many other helpful tips:
https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=324087

The Advanced Networking forum has a sticky about OpenVPN with the OpenVPN Client Setup guide which already has a paragraph about Surfshark you might take a look.

Furthermore your DNS settings are wrong, DNS settings are handled by the OpenVPN client.
Remove the Local DNS and keep it at its default 0.0.0.0.
Use for Static DNS 1 and 2 trusted publicly available DNS servers e.g. 9.9.9.9, 1.0.0.1

[Frakko]

Thanks for the advice. I would like to improve the performance of the router with the VPN and I would like to know, if possible, at the encryption level (pre-set) what do you advise me to keep and what do you advise me to put a not set or none or at what encryption level should I keep these options
(First Data Cipher, Second Data Cipher, Third Data Cipher)

[egc]

There is not much you can do as the encryption cipher plays only a minor role in the speed.
Besides the encryption is set by the server side and most probably it is AES-256-GCM.

CHACHA-POLY is a little bit faster.
So as first data-cipher set CHACHA-POLY, second AES-128-GCM, third AES-256-GCM.

But chances are that the server will simply set AES-256-GCM.
You can view this in the OpenVPN log.

If you want three times the performance of OpenVPN use WireGuard