Hello, and welcome!
OpenBSD's built-in NFS client only supports the NFS Version 2 and 3 protocols. According to
Oracle, the server and clients can be restricted to using Version 4 by configuration settings in the Solaris configuration file /etc/default/nfs. You may want to ensure you permit Version 3, which is the default protocol used by
mount_nfs(8).
But Oko is right; a LOT more information about the network environment would be helpful. It's hard for us to help you when we're over here, way far away at the other end of the Internet. We only have what you tell us to try to help you. Some of the things we might want to know:
- Is the interconnection between Solaris server to OpenBSD wired end-to-end, or is there any network segment using wireless?
- Are VLANs in use?
- Are the two devices on the same network segment, or is there a router or bridge between them? (And yes, a WiFi access point on a wired network is actually a bridge.)
- What NIC/PHY are being used on the OpenBSD client?
- How is the media configured? (Duplex, speed, etc.)
- Are you using UDP or TCP for NFS? OpenBSD's client uses UDP by default.
- Have you run tcpdump(8) or other network monitors to watch the traffic between client and server? Was there an indication of which platform ceased communication?
These are the questions I would have, as a starting point.
Luckily, everything of interest about the OpenBSD components and the hardware you are using for OpenBSD can pretty much be answered by providing a
dmesg(8).