More detail on the problem. after starting remote-viewer --debug, I get (remote-viewer.exe:18308): virt-viewer-DEBUG: 11:45:30.594: New spice channel 000000000608B240 SpiceMainChannel 0 (remote-viewer.exe:18308): virt-viewer-DEBUG: 11:45:30.594: notebook show status 0000000003479130 (remote-viewer.exe:18308): Spice-WARNING **: 11:45:30.691: ../subprojects/spice-common/common/ssl_verify.c:444:openssl_verify: Error in certificate chain verification: self signed certificate in certificate chain (num=19:depth1:/C=US/O=xxxxxxxxxx.65101) (remote-viewer.exe:18308): GSpice-WARNING **: 11:45:30.692: main-1:0: SSL_connect: error:00000001:lib(0):func(0):reason(1) (remote-viewer.exe:18308): virt-viewer-DEBUG: 11:45:30.693: Destroy SPICE channel SpiceMainChannel 0 So it seems like there's some additional thing that needs telling to use the official signed cert. Any clues for me please?