Has anyone here had real experience with the BenQ CS-01 in their meeting rooms? I'm running into some frustrating issues with it — particularly with wireless screen sharing (InstaShare), multi-user collaboration, and occasional lag or connection drops when multiple people are presenting. The image quality is good, but we're seeing problems with reliability during daily use.

I had similar issues with the BenQ CS-01 in our meeting room, especially with InstaShare wireless sharing and lag when multiple people connect.
Here are the specific solutions that worked for us (all taken directly from the official manual here https://en.manual.ly/benq/benq-cs-01/manual): Make sure you’re using InstaShare 2 (the latest version). The older InstaShare app causes frequent drops. Go to Settings > Wireless > InstaShare on the CS-01 and enable “Allow multiple users” + set the connection mode to “Fast” instead of “Standard”. For best stability, connect the display via a wired Ethernet cable instead of only Wi-Fi. The manual strongly recommends this for conference rooms with heavy use. When multiple devices are sharing, have users join using the InstaShare ID + 4-digit code shown on the screen rather than scanning the QR code — it seems more reliable. Update the firmware of the CS-01. There was a newer version that improved wireless performance and reduced lag. After applying these (especially Ethernet + InstaShare 2 + firmware update), the multi-user experience became much smoother. It’s not perfect for 6+ people talking at once, but for 3–4 users it now works well.

I’ve been following this thread but haven’t used the BenQ CS-01 myself. From what I’ve read in the manual and seen in reviews, it seems decent for basic wireless sharing with 2–3 users, but it looks like it struggles a bit when more people try to connect at the same time.
The manual does recommend using Ethernet and InstaShare 2 for better performance, as mentioned above. Might be worth trying those tweaks before deciding to return or replace it.