Error is

2026-04-24T11:52:44.6272028Z ssl_openssl.c: In function 'cert_verify_callback':
2026-04-24T11:52:44.6273876Z ssl_openssl.c:321:5: error: implicit declaration of function 'X509_STORE_CTX_set0_crls'; did you mean 'X509_STORE_CTX_get0_cert'? [-Wimplicit-function-declaration]
2026-04-24T11:52:44.6275528Z   321 |     X509_STORE_CTX_set0_crls(ctx, session->opt->ssl_ctx->crls);
2026-04-24T11:52:44.6276549Z       |     ^~~~~~~~~~~~~~~~~~~~~~~~
2026-04-24T11:52:44.6277119Z       |     X509_STORE_CTX_get0_cert
2026-04-24T11:52:44.6287431Z ssl_openssl.c: In function 'tls_ctx_set_options':
2026-04-24T11:52:44.6288618Z ssl_openssl.c:343:35: warning: conversion from 'uint64_t' {aka 'long long unsigned int'} to 'long int' may change value [-Wconversion]
2026-04-24T11:52:44.6289834Z   343 |     SSL_CTX_set_options(ctx->ctx, sslopt);
2026-04-24T11:52:44.6290533Z       |                                   ^~~~~~

The patch should be restored, unless openwrt/openwrt#23072 is merged. @commodo

Still the same error.
git blame shows that the new API is introduced by OpenVPN/openvpn@0588668.

Related issue: wolfSSL/wolfssl#10309

WolfSSL is not officially supported by OpenVPN. Since WolfSSL is not OpenWrt's default SSL library, I suggest either drop the variant or wait for WolfSSL to keep up. Your thoughts?

Reverting OpenVPN/openvpn@0588668 and OpenVPN/openvpn@c3dd2ab fixes the build.

WolfSSL is not officially supported by OpenVPN. Since WolfSSL is not OpenWrt's default SSL library, I suggest either drop the variant or wait for WolfSSL to keep up. Your thoughts?

Why is OpenWrt still supporting wolfSSL at all? It was selected as default in 19.07 (I think, or was it 18.06?), but then switched back to MbedTLS due to wolfSSL's lack of a long-term support (LTS) release and its unstable ABI, which causes packages relying on it to break during minor updates.

I think this should fix it? wolfSSL/wolfssl@b9514e7

I think this should fix it? wolfSSL/wolfssl@b9514e7

This fixed another issue, but not related to the one I mentioned.

OpenVPN 2.7.3 has been released, so I'm closing this. I'll create a new PR later