Flash Memory upgrade on TP LINK 845n v4

I have TP LINK 845nv4 router with 4MBit (cfeon q32b-104hip) flash memory and 256MB RAM (Model No A3S56D40GTP-50) and Mediatek chipset MT7628NN.
Because of Flash Memory Constraints I`m unable to flash my router.
Anyone can share steps to change flash memory and flash it with Openwrt?

Can't see it being supported

While MT7628NN is supported (I believe), your device needs to be ported - this isn't like installing an OS onto an x86/x86_64 system.

4 MiB might still work for a barebones system (no web interface etc) but no guarantees. If you can replace your flash chip with a (compatible!) bigger model, you could have a look at porting. But they're two separate issues.

If i do porting of flash chip it will be enough for install openwrt
Can you share any link or steps for porting flash chip

If you're looking for an easy solution, replace the hardware. If you have to ask about it, you're not going to get it done. It not only involves soldering, but also recomposing a new partitioning structure, writing it externally with an spi-nor writer and patching (and building) the source in multiple places - and having to keep doing so for 'all eternity' (the remaining lifetime of your device), it's not going to be or trivial - but spending ~10 bucks on better (used) hardware is.