一般需要检查环境变量是否配置正确，数据库重启等操作
可以按这个文档步骤检查一下：https://eco.dameng.com/community/article/4ec1678763ac996d86ab74f74492de5f
另外可以更换oracle的instantclient试试

是创建的什么环境之间的dblink,比如oracle到达梦，mysql到达梦？检查下环境变量看看LD_LIBRARY_PATH

--看下是不是libnsl.so.1依赖缺失导致的
[dmdba@localhost instantclient_19_19]$ ldd libclntsh.so
linux-vdso.so.1 (0x00007ffd79344000)
libnnz19.so (0x00007fdb099f8000)
libdl.so.2 => /usr/lib64/libdl.so.2 (0x00007fdb099d7000)
libm.so.6 => /usr/lib64/libm.so.6 (0x00007fdb09854000)
libpthread.so.0 => /usr/lib64/libpthread.so.0 (0x00007fdb09833000)
libnsl.so.1 => not found
librt.so.1 => /usr/lib64/librt.so.1 (0x00007fdb09828000)
libaio.so.1 => /usr/lib64/libaio.so.1 (0x00007fdb09821000)
libresolv.so.2 => /usr/lib64/libresolv.so.2 (0x00007fdb09808000)
libc.so.6 => /usr/lib64/libc.so.6 (0x00007fdb09650000)
/lib64/ld-linux-x86-64.so.2 (0x00007fdb0e1d5000)
libclntshcore.so.19.1 (0x00007fdb090ab000)
libnsl.so.1 => not found

--没有libnsl.so.2
[dmdba@localhost instantclient_19_19]$ ls -lrt /usr/lib64 | grep libnsl
-rwxr-xr-x 1 root root 96368 4月 2 2022 libnsl.so.2.0.1
lrwxrwxrwx 1 root root 15 4月 2 2022 libnsl.so.2 -> libnsl.so.2.0.1

--创建软连接
[root@localhost lib64]# ln -s libnsl.so.2 libnsl.so.1

[root@localhost instantclient_19_19]# ldd libclntsh.so
linux-vdso.so.1 (0x00007fffdf5e9000)
libnnz19.so (0x00007f454aa78000)
libdl.so.2 => /usr/lib64/libdl.so.2 (0x00007f454aa57000)
libm.so.6 => /usr/lib64/libm.so.6 (0x00007f454a8d4000)
libpthread.so.0 => /usr/lib64/libpthread.so.0 (0x00007f454a8b3000)
libnsl.so.1 => /lib64/libnsl.so.1 (0x00007f454a898000)
librt.so.1 => /usr/lib64/librt.so.1 (0x00007f454a88d000)
libaio.so.1 => /usr/lib64/libaio.so.1 (0x00007f454a886000)
libresolv.so.2 => /usr/lib64/libresolv.so.2 (0x00007f454a86d000)
libc.so.6 => /usr/lib64/libc.so.6 (0x00007f454a6b5000)
/lib64/ld-linux-x86-64.so.2 (0x00007f454f255000)
libclntshcore.so.19.1 (0x00007f454a110000)
libtirpc.so.3 => /usr/lib64/libtirpc.so.3 (0x00007f454a0e0000)
libgssapi_krb5.so.2 => /usr/lib64/libgssapi_krb5.so.2 (0x00007f454a088000)
libkrb5.so.3 => /usr/lib64/libkrb5.so.3 (0x00007f4549fa2000)
libk5crypto.so.3 => /usr/lib64/libk5crypto.so.3 (0x00007f4549f89000)
libcom_err.so.2 => /usr/lib64/libcom_err.so.2 (0x00007f4549f83000)
libkrb5support.so.0 => /usr/lib64/libkrb5support.so.0 (0x00007f4549f71000)
libkeyutils.so.1 => /usr/lib64/libkeyutils.so.1 (0x00007f4549f6a000)
libcrypto.so.1.1 => /usr/lib64/libcrypto.so.1.1 (0x00007f4549c7e000)
libselinux.so.1 => /usr/lib64/libselinux.so.1 (0x00007f4549c52000)
libz.so.1 => /usr/lib64/libz.so.1 (0x00007f4549c38000)
libsecurity.so.0 => /usr/lib64/libsecurity.so.0 (0x00007f4549c33000)
libpcre2-8.so.0 => /usr/lib64/libpcre2-8.so.0 (0x00007f4549b9e000)