I have also had this problem several months now without finding any solutions.
What do you mean about gateway/routes?
I have this on 5 2020's and 1 dual controller 2050 that are placed in different parts of the world and all can communicate nicely with everything else, so there is no indication that the problem is related to gateway/routing.
If you accept the certificates permanently then you might have to clean it up from the browser cache. In this case you better re-run the SSL setup or don't save the certificate in permanent way until unless you are going to keep the SSL certificate common.
While searching for snmpd error message, I saw in this thread couple of you had the same problem. We recently getting this error message on the command line interface. I am wondering did you find solution for the problem. If it is, please can you reply about how did you fix the problem. I really appreciate any feedback.
Sat Apr 23 09:04:55 EDT [netapp2050-2: snmpd:error]: -- .18.104.22.168.22.214.171.124.1.16.3
Sat Apr 23 09:04:59 EDT [netapp2050-2: snmpd:error]: send response:
Sat Apr 23 09:09:55 EDT [netapp2050-2: snmpd:error]: -- .126.96.36.199.188.8.131.52.1.16.3
Sat Apr 23 09:09:59 EDT [netapp2050-2: snmpd:error]: -- .184.108.40.206.220.127.116.11.1.16.2