Synapse 2.0 unable to login anymore.

Hello, For some reason I'm no longer able to log into Synapse 2.0 and I can't for the life of me work out why. The login information I'm using is correct of that I can be sure. it's not being blocked by my firewall in any way shape or form but each time I attempt to login I'm getting an invalid username / password error even though they are correct. (as proved by the fact I'm able to post this using the same account. I've attempted to reinstall Synapse to no avail, reset my password and to be honest I'm unsure what to try next. (I'm unable to update to synapse 3.0 due to the fact i'm using old peripherals that it doesn't support.) I'd be very thankful for any tips or information anyone could give me.