Syncthing has built-in encryption and works pretty well, it’s also really easy to use. I have been using it for some time with several instances and never had a problem, it requires more CPU though, so some old raspies had a hard time working with my big photos folder (800GB) when encrypted.

Not sure how secure it is, but from the docs: Encryption is XChaCha20-Poly1305 and AES-SIV with a key derived from the password and folder ID using scrypt. Considering how polished, huge user base and how much attention to detail Syncthing has, I trust it’s good enough for my needs.