Change 192.168.88.1/24 to 192.168.1.1/24 (RB750, tried quickset)

I bought a RB750GL, connected the Mikrotik routerboard from my ISP (where I got admin access) to Port 1.
By default (DHCP 192.168.88.1) it works fine (the ISP routerboard is on 192.168.1.1).

I want to change RB750GL to 192.168.1.1 (DHCP, etc as several devices have already a static IP in that range) and firewall off the ISP router board and just get internet access from it.

I tried this, see screenshot of my settings - WebFig Quick Set: https://ibb.co/bS8z35

current:
ISP (WiFi-WAN) ↔ Mikrotik router provided by ISP (DHCP 192.168.1.1/24) ↔ my LAN (192x168.1.x)

What works:
ISP (WiFi-WAN) ↔ Mikrotik router provided by ISP (DHCP 192.168.1.1/24) ↔ Mikrotik RB750GL (DHCP 192.168.88.1/24) ↔ my LAN (192x168.88.x)

What I want:
ISP (WiFi-WAN) ↔ Mikrotik router provided by ISP (DHCP 192.168.x.x ??) ↔ Mikrotik RB750GL (DHCP 192.168.1.1/24) ↔ my LAN (192x168.1.x)

Obviously I want my LAN shielded off, and just access internet.

(I have some network knowledge with Cisco ios, Linksys routers and some limited experience with the routerboard from my ISP)

I run “/export”, that’s the “What works” I listed above

[admin@MikroTik] > /export
# apr/16/2017 10:44:31 by RouterOS 6.38.5
/interface ethernet
set [ find default-name=ether2 ] name=ether2-master
set [ find default-name=ether3 ] master-port=ether2-master
set [ find default-name=ether4 ] master-port=ether2-master
set [ find default-name=ether5 ] master-port=ether2-master
/ip neighbor discovery
set ether1 discover=no
/ip pool
add name=default-dhcp ranges=192.168.88.10-192.168.88.254
/ip dhcp-server
add address-pool=default-dhcp disabled=no interface=ether2-master name=defconf
/ip address
add address=192.168.88.1/24 comment=defconf interface=ether2-master network=\
    192.168.88.0
/ip dhcp-client
add comment=defconf dhcp-options=hostname,clientid disabled=no interface=ether1
/ip dhcp-server network
add address=192.168.88.0/24 comment=defconf gateway=192.168.88.1
/ip dns
set allow-remote-requests=yes
/ip dns static
add address=192.168.88.1 name=router
/ip firewall filter
add action=accept chain=input comment="defconf: accept ICMP" protocol=icmp
add action=accept chain=input comment="defconf: accept established,related" \
    connection-state=established,related
add action=drop chain=input comment="defconf: drop all from WAN" in-interface=\
    ether1
add action=fasttrack-connection chain=forward comment="defconf: fasttrack" \
    connection-state=established,related
add action=accept chain=forward comment="defconf: accept established,related" \
    connection-state=established,related
add action=drop chain=forward comment="defconf: drop invalid" connection-state=\
    invalid
add action=drop chain=forward comment=\
    "defconf:  drop all from WAN not DSTNATed" connection-nat-state=!dstnat \
    connection-state=new in-interface=ether1
/ip firewall nat
add action=masquerade chain=srcnat comment="defconf: masquerade" out-interface=\
    ether1
/tool mac-server
set [ find default=yes ] disabled=yes
add interface=ether2-master
/tool mac-server mac-winbox
set [ find default=yes ] disabled=yes
add interface=ether2-master

Changing through UI all IP from 192.168.88.x to 192.168.1.x (aka “What I want works”) didn’t work - I can’t access the internet.

You cannot assign overlapping or the same networks to two interfaces and try to route between them.

How can I solve this? I want to keep my LAN to 192.168.1.x

Is the best way to change the IP address of the ISP provided router to 192.168.2.1 and set my RB750GL to 192.168.1.1 ?

P.S. The ISP lists as possible service: change router to bridge-mode … $200 USD. As I have full admin access to the MikroTik router (it looks like a MikroTik “SXT 5 ac” router+antenna), changing to bridge-mode is it do-able by myself too, right?

Such price is dirty blackmail. Nothing more.

There are many options. Use whatever else network subnet for your lan. Don’t use additional router. Pay the price for mode change. Do it yourself. Ask the isp to change the network subnet. Change the isp. And others for sure…