Probably not, because there is more stuff in newer versions of everything, and the flash chip is too small. When you start with a release build and opkg remove packages that shipped with it, that doesn't actually free up any space. You have to build the ROM without them in the first place.
OK. It will be so hard to to that. Is there any other way to use
wpa2 enterprise - authentication via Identity and Password ?
For my other router WR841ND I have found Attitude Adjustement 12.9 and there installed wpa manually. And for WR941ND it is only for v2, v3, v4. But I have v5
So Can I just upgrade my router by
gargoyle-1.6.2.2-ar71xx-tl-wr941nd-v5-squashfs-sysupgrade.bin
Or should I use:
gargoyle-1.6.2.2-ar71xx-tl-wr941nd-v5-squashfs-factory.bin
or it is not possible now to install gargoyle if I have OpenWRT 18?
It should work to use the sysupgrade, since those Gargoyle builds are based on OpenWrt.
Though the safest way to change from one third-party firmware to another is to restore the factory firmware first, then install anew with a "factory" build. "Factory" builds are only used to flash from factory firmware to OpenWrt. Never flash them from within OpenWrt.