Web Interface Not Accessible

Ok, so an update. 

Downgraded the firmware in one of the GS108Ev3 switches to see if that was the cause but this did not fix the issue.

I've disabled the computer firewall in case that was the problem but that did not fix the issue either.

If I log on to the GS110TP, I can ping the GS108Ev3 (as mentioned earlier, I can also ping from the computer too) so this confirms some comms to the switch.

I borrowed another switch, this time a GS105Ev2 (I believe these are the same switch only a different number or ports) and when I plugged it in, I can access its web interface so on the face of it looks like an issue with the specific GS1008Ev3 switches - but I am not so sure.

When I connected the GS105Ev2 I accidentally connected it to the router which essentially meant I had a direct connection from my computer to the switch and I could access the web interface so as a test, I used a cable to connect directly to the GS1008Ev3 switch and I found I could access the web interface.

Clearly this is not very useful as due to wiring constraints, I have difficulty locating the switches in readiy accessible places so need  the web interface to work.

So, on the face of it, it looks like the GS110TP is somehow blocking the web interface on the GS108Ev3...

Are there any settings which would interfere with this?