Can anyone help me solve a network problem?

For years and years my media /web server has had the same local ip address and over those years that ip (192.168.1.100) got really entrenched. Now, I've had to change its address because I moved and the only way to get something even approaching usable internet speeds was to use a hybrid cell/DSL router from the telecom. That router wouldn't let me use 192.168.1.xxx; the closest I could set it to was 192.168.2.xxx. So, I changed the 1 to a 2 everywhere i could find it, but still couldn't get on the internet. I tried setting network manager to use automatic dhcp, but still couldn't get online. The correct (new) ip showed up when I queried it and was in the gui info, but still nothing: "no route to host".

What I stumbled on is that when I pinged there was the old ip:

htpc@htpc:~$ ping -c5 198.252.206.24
PING 198.252.206.24 (198.252.206.24) 56(84) bytes of data. From 192.168.1.100 icmp_seq=1 Destination Host Unreachable From 192.168.1.100 icmp_seq=2 Destination Host Unreachable From 192.168.1.100 icmp_seq=3 Destination Host Unreachable From 192.168.1.100 icmp_seq=4 Destination Host Unreachable From 192.168.1.100 icmp_seq=5 Destination Host Unreachable
--- 198.252.206.24 ping statistics --- 5 packets transmitted, 0 received, +5 errors, 100% packet loss, time 4098ms pipe 4

[but then if I do this...]
htpc@htpc:~$ sudo ip route add default via 192.168.2.1
[presto]
htpc@htpc:~$ ping -c5 198.252.206.24
PING 198.252.206.24 (198.252.206.24) 56(84) bytes of data. 64 bytes from 198.252.206.24: icmp_seq=1 ttl=54 time=115 ms 64 bytes from 198.252.206.24: icmp_seq=2 ttl=54 time=116 ms 64 bytes from 198.252.206.24: icmp_seq=3 ttl=54 time=116 ms 64 bytes from 198.252.206.24: icmp_seq=4 ttl=54 time=114 ms 64 bytes from 198.252.206.24: icmp_seq=5 ttl=54 time=116 ms
--- 198.252.206.24 ping statistics --- 5 packets transmitted, 5 received, 0% packet loss, time 4005ms rtt min/avg/max/mdev = 114.835/115.828/116.216/0.663 ms

I know the output is old, but I have tried clearing the ARP table since then, but this is still ongoing.
I've now tried to install Bubbleupnp and though i go to the correct address to get the web interface, it's listening on the old, nonexistent address