Hi @Cv1 . These articles may help you improve the wifi range.
If you don't want to move the router (you might have ethernet devices already), you can try a wifi extender. It is placed partway between the router and your office.
If you have FTTB/FTTC/FTTN that use the telephone wall outlet and you have a second telephone outlet, you can connect into that. Only one telephone outlet can be used. Or try a telephone extension cable.
If you have HFC/FTTP, you could try a longer ethernet cable (CAT6) between the NBN box and the router.