pushing netcfg when using IPv4 topology on mininet

[URIB4u]

I noticed that the interfaces of the switches were given an IPv6 gateway address, and they work even if I am using IPv4. My question is do I need to change those interface addresses to IPv4? I tried it but the netcfg can't be pushed. I keep getting error 500

[h-afsatariq]

I am also trying to work with ipv4 hosts in this testbed but am facing multiple problems. Did you find any solution to it?