I was using FT8 through a remote in RCForb. Reception in FT8 is spotty through the remote. I do not have an HF rig to test if the remote is the problem. So far, I think it is the delay through the internet that is causing the spotty reception, just as receiving would be difficult if your computer clock was off by 0.6 seconds. Is there a way to also delay the decoding in WSJT-X?
When you suspect timing problems with FT8 decodes, simply manually adjust your computer clock to see if the situation improves. This is also the standard recommendation when you suspect the transmitting station's clock is off.
It is quite possible that you are having timing issues since the Internet is nondeterministic. It is not uncommon that in a multipacket transmission that a packet that was sent earlier will arrive after a packet that was sent later. Requests for resends of bad or missing packets contributes to nondeterminism. If the packet is sent via a connectionless protocol, such as simple UDP messaging, packet loss is also common.
The audio CODEC used in RCForb will also play a role in the success rate of FT8 decodes. It certainly introduces latency on both ends of the connection that may affect FT8 timing. It may also alter the effective audio bandwidth and bandwidth shape which can raise havoc with FT8 decodes.