I have a problem to access certain sites that are located in the same network address space as my Deco LAN IP.

When I configure my Deco LAN IP as 172.16.0.1 (255.255.255.0) I can't access 172.217.21.170 (which is fonts.googleapis.com).

Pinging fonts.googleapis.com [172.217.21.170] with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.

Tracing route to fonts.googleapis.com [172.217.21.170]
over a maximum of 30 hops:

  1     1 ms     2 ms     1 ms  172.16.0.1
  2     *        *        *     Request timed out.
  3     *        *        *     Request timed out.
  4     *        *        *     Request timed out.
  5     *        *        *     Request timed out.
  6     *        *        *     Request timed out.

If I change my LAN IP as 192.168.0.1 (255.255.255.0) the address above works.

Tracing route to fra07s64-in-f170.1e100.net [172.217.21.170]
over a maximum of 30 hops:

  1     1 ms     1 ms     3 ms  192.168.0.1
  2     2 ms     1 ms     1 ms  192.168.8.1
  3     *        *        *     Request timed out.
  4    56 ms    23 ms    32 ms  10.64.127.1
  5    51 ms    28 ms    32 ms  213.192.186.78
  6    26 ms    32 ms    31 ms  213.192.186.77
  7    54 ms    29 ms    29 ms  213.192.184.65
  8    52 ms    31 ms    56 ms  213.192.185.93
  9    31 ms    35 ms    38 ms  142.250.213.185
 10    50 ms    49 ms    47 ms  209.85.242.11
 11    42 ms    57 ms    56 ms  fra07s64-in-f170.1e100.net [172.217.21.170]

Trace complete.

The problem is that then it can't access ip addresses in 192.x.x.x space

Tracing route to 192.229.221.185 over a maximum of 30 hops

  1     1 ms     1 ms     1 ms  192.168.0.1
  2     *        *        *     Request timed out.
  3     *        *        *     Request timed out.
  4     *        *        *     Request timed out.

I can't use 10.x.x.x address space for my LAN IP as it's used by WAN provider.

I've a mobile router in bridged mode as internet backhaul where my deco is connected using ethernet.

Any help what to try next?