Manually updated my 2927 router from 4.5.2 to 4.5.2.1 over this Easter weekend to find that following the update I can't access the login page using Microsoft Edge (just get a completely blank page). I've been chatting to Draytek UK support today and it seems this may be an issue with the way Edge deals with the Certificate for the login page of this particular firmware. Other browsers (Chrome, Firefox etc) seem OK. I ended up having to downgrade to the previous firmware (4.5.2) using an alternative browser to resolve the problem. Hopefully Draytek can sort out a fix for this and make it available in the next firmware update. I thought I'd post this for anyone with similar problems.

I have a 2927ax on 4.5.2.1 and don't see any issues with Edge

EDIT - I apologise, I read your post too quickly and didn't clock that you were using a Certificate.  As a home user I have no need of that and use http login.

For me (also 2927ax) both Chrome and Edge work the same.

Neither would log in securely due to a certificate complaint (the browser seemed to be seeing the DDNS certificate and I was accessing the router via IP address).

If I used http (rather than https) all was well.

Since I've never attempted a secure connection before I can't say whether 4.5.2 or previous versions were different in this respect.

I'm OK with insecure access personally but I'm a domestic user.

With non-WiFi 2927 I see this problem only with Firefox. All of Edge, Chrome and Opera have no difficulties.

Not a caching issue by any chance. Try clearing the history and disabling any third party plugins.