It seems to make no difference if I switch subnet. But it does show that my client machine is confused. So my home subnet is now 192.168.9.x. My office subnet is 192.168.0.x

When I SSL Tunnel in, I cannot ping anything on 192.168.0.x network but can continue to ping 192.168.9.x which implies that I am not properly hooked in to the office network.

Can you ping the router's 192.168.0.x IP ?

.. and the remote client gets assigned the specified IP

Did you specify this ? I presume the IP is 192.168.0.something ?

I have tried setting up the SSL VPN to (a) assign the client via DHCP and (b) assign a specified IP (yes, in the 192.168.0.x range). Neither approach seems to work.

I believe the client device would need to have DHCP enabled so as to get assigned IP over the SSL VPN. What does an IPCONFIG show for IP/Gateway when you have the tunnel up?

Ewith tunnel established I get this:

PPP adapter DraySSLTunnel:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : DraySSLTunnel
Physical Address. . . . . . . . . :
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
IPv4 Address. . . . . . . . . . . : 192.168.0.119(Preferred) <======== this is the IP address assigned by the 2860n to incoming VPN connection
Subnet Mask . . . . . . . . . . . : 255.255.255.255
Default Gateway . . . . . . . . . : 0.0.0.0
DNS Servers . . . . . . . . . . . : 212.159.6.10
212.159.6.9
NetBIOS over Tcpip. . . . . . . . : Enabled

Wireless LAN adapter Wi-Fi:

Connection-specific DNS Suffix . : Home
Description . . . . . . . . . . . : Marvell AVASTAR Wireless-AC Network Controller
Physical Address. . . . . . . . . : 4C-0B-BE-02-DF-20
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IPv6 Address. . . . . . . . . . . : 2a02:c7d:b348:7f00:f1f3:ab5f:e4f8:94eb(Preferred)
IPv6 Address. . . . . . . . . . . : fdab:cf30:f80c:0:f1f3:ab5f:e4f8:94eb(Preferred)
Temporary IPv6 Address. . . . . . : 2a02:c7d:b348:7f00:68d4:2f71:d39a:debf(Preferred)
Temporary IPv6 Address. . . . . . : fdab:cf30:f80c:0:6190:8ed0:8293:7cff(Preferred)
Link-local IPv6 Address . . . . . : fe80::f1f3:ab5f:e4f8:94eb%21(Preferred)
IPv4 Address. . . . . . . . . . . : 192.168.9.4(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Lease Obtained. . . . . . . . . . : 05 January 2017 10:13:00 AM
Lease Expires . . . . . . . . . . : 06 January 2017 10:13:01 AM
Default Gateway . . . . . . . . . : fe80::9221:6ff:fe0b:5b20%21
192.168.9.1
DHCP Server . . . . . . . . . . . : 192.168.9.1
DHCPv6 IAID . . . . . . . . . . . : 357305278
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-1D-4F-E5-98-4C-0B-BE-02-DF-20
DNS Servers . . . . . . . . . . . : 192.168.9.1
NetBIOS over Tcpip. . . . . . . . : Enabled

Well the IPv4 bit looks like mine. Only real difference is that I have IPv6 disabled on this particular client device (though it is enabled and working on my router).