How do I get rid of 'Invalid Certificate' Error in IE7?

My NAS is at 192.168.0.10 in my home network. My ISP IP address is a.b.c.d. I have setup my router to port forward accordingly. When at home, I prefer to access the NAS locally using https://192.168.0.10, but my extended family will access the NAS remotely using https://a.b.c.d. Using the instructions above for trusted sites and certificate generation/import, I can eliminate the "invalid certificate" problem for either local access via 192.168.0.10 or remote access via a.b.c.d, but not BOTH at the same time.

I have tried adding both 192.168.0.10 and a.b.c.d simultaneously to trusted sites and import the current certificate accordingly. Experimentally, if I use 192.168.0.10 as the NAS SSL key host, then I will see no invalid certificate error when contacting the NAS via 192.168.0.10, but I will see certificate error when contating the NAS via a.b.c.d. If I use a.b.c.d as the NAS SSL key host, then I will see no invalid certificate error when contacting the NAS via a.b.c.d, but I will see certificate error when contating the NAS via 192.168.0.10. If I use a random name as the NAS SSL key host, I will see certificate error when contacting the NAS via 192.168.0.10 or a.b.c.d.

Am I doing something wrong or is there a way to overcome this ?