Check the dashboard for REF001 - http://ref001.dstargateway.org/
Search for your callsign and ensure you don't have another connection to it. If you can connect with your Openspot, there will probably be a "D" appended to the end of your callsign.
Scroll all the way to the bottom of the page and see how many "remote users" (hotspots) are connected to it. The REF reflectors support a finite number of connections. This one allows about 853 before it starts disallowing others to connect.
Unfortunately many users aren't aware of this and park their hotspots on REF001C 24x7 and lock others out. I always unlink (or turn off) my OS4 Pro when I'm not actively using it. While unlinking put the OS4 in a null connection (openspot special connector active), one can exit the mode by changing reflectors or changing it in the web gui. btw, REF0030 allows ~ 900 remote users.