我正在尝试与仅限 NFSv4服务器。但客户端尝试降级协议版本：
mount -v -t nfs -o nfsvers=4 my-nfsv4-only.server:/exports/storagetest storagetest
mount.nfs: timeout set for Wed Oct 27 16:16:28 2021
mount.nfs: trying text-based options 'vers=4,addr=XX.XX.XX.XX,clientaddr=YY.YY.YY.YY'
mount.nfs: mount(2): No such file or directory
mount.nfs: trying text-based options 'addr=XX.XX.XX.XX'
mount.nfs: prog 100003, trying vers=3, prot=6
mount.nfs: trying XX.XX.XX.XX prog 100003 vers 3 prot TCP port 2049
mount.nfs: portmap query retrying: RPC: Program/version mismatch
mount.nfs: prog 100003, trying vers=3, prot=17
mount.nfs: portmap query failed: RPC: Program not registered
mount.nfs: requested NFS version or transport protocol is not supported
服务器是全新的 Debian 11，客户端是 Ubuntu 20.04 和 Debian 11。同样的问题。
任何想法？