Wireless Controller 7500 upgrade to 6.5.5.18 from 6.0.1.0

Hi,

Apologies if this has been raised elsewhere but I couldnt find a relevant issue identical to mine.

I am remote from the office where my WC7500 exists.

I remoted on to a PC on the appropriate network, backed up the exisitnf 6.0.1.0 firmware and kicked off the upgrade process to 6.5.5.18.

I have none of the listed WACs in my network so went straight to the biggie.

Took a while then came back with the following message

Site cant provide a secure connection

Site 192.168.x.x uses an unsupported protocol

ERR_SSL_VERSION_OR_CIPHER_MISMATCH

the Client or server dont support a common SSL protocol version or cipher suite.

Now I guess this means I have to drop an appropriate cerificate onto my PC which I am trying to login with but where do I pick one up?

Any advice appreciated, I went into the office the other day and thankfully the controller is still working, but I dont want to reboot it in case I have problems getting it to recognise WAPs again