Redirecting nextcloud URL

sgw

old nextcloud runs without HAproxy behind a portforwarding (443, SSL/TLS on the box itself) and is reached via:

new nextcloud is inside a docker container and behind HAproxy (SSL/TLS offloading)

The old links should stay valid ... for example calendar links like:

should be kept working while also this should work:

Should/could that be solved on the level of HAproxy or should I better write some Rewrite-statements in the target apache?

I assume there are multiple ways to solve that, and I wonder if someone could help me to find the most elegant and reliable solution.